[DOCS] Update the docs & blogs for 1.5.1 release (#1425)

diff --git a/docs/_blog/2020-08-28-announcing-the-release-of-apache-samza--1.5.1.md b/docs/_blog/2020-08-28-announcing-the-release-of-apache-samza--1.5.1.md
new file mode 100644
index 0000000..dc9d6d7
--- /dev/null
+++ b/docs/_blog/2020-08-28-announcing-the-release-of-apache-samza--1.5.1.md
@@ -0,0 +1,78 @@
+---
+layout: blog
+title: Announcing the release of Apache Samza 1.5.1
+icon: git-pull-request
+authors:
+    - name: Bharath Kumarasubramanian
+      website:
+      image:
+excerpt_separator: <!--more-->
+---
+
+<!--
+   Licensed to the Apache Software Foundation (ASF) under one or more
+   contributor license agreements.  See the NOTICE file distributed with
+   this work for additional information regarding copyright ownership.
+   The ASF licenses this file to You under the Apache License, Version 2.0
+   (the "License"); you may not use this file except in compliance with
+   the License.  You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+-->
+
+# **Announcing the release of Apache Samza 1.5.1**
+
+<!--more-->
+
+We are thrilled to announce the release of Apache Samza 1.5.1.
+
+### Bug Fixes:
+In 1.5 release, we enabled transactional state by default for all samza jobs. We identified a critical bug related to trimming the state and have addressed the issue in 1.5.1.
+For applications that are already on Samza 1.5.0, updating your dependencies to use Samza 1.5.1 should be sufficient to upgrade.
+For applications that are on version 1.4 & below, please follow the upgrade instructions below.
+
+
+### Upgrading your application to Apache Samza 1.5.0
+ConfigFactory is deprecated as Job Runner does not load full job config anymore. Instead, ConfigLoaderFactory is introduced to be executed on ClusterBasedJobCoordinator to fetch full job config.
+If you are using the default PropertiesConfigFactory, simply switching to use the default PropertiesConfigLoaderFactory will work, otherwise if you are using a custom ConfigFactory, kindly creates its new counterpart following ConfigLoaderFactory. 
+
+Configs related to job submission must be explicitly provided to Job Runner as it is no longer loading full job config anymore. These configs include
+
+* Configs directly related to job submission, such as yarn.package.path, job.name etc.
+* Configs needed by the config loader on AM to fetch job config, such as path to the property file in the tarball, all of such configs will have a job.config.loader.properties prefix.
+* Configs that users would like to override
+
+Full list of the job submission configurations can be found [here](https://cwiki.apache.org/confluence/display/SAMZA/SEP-23%3A+Simplify+Job+Runner#SEP23:SimplifyJobRunner-References)
+
+#### Usage Instructions
+Alternative way when submitting job,
+{% highlight bash %}
+deploy/samza/bin/run-app.sh
+ --config yarn.package.path=<package_path>
+ --config job.name=<job_name>
+{% endhighlight %}
+can be simplified to
+{% highlight bash %}
+deploy/samza/bin/run-app.sh
+ --config-path=/path/to/submission/properties/file/submission.properties
+{% endhighlight %}
+where submission.properties contains
+{% highlight jproperties %}
+yarn.package.path=<package_path>
+job.name=<job_name>
+{% endhighlight %}
+
+#### Rollback Instructions
+In case of a problem in Samza 1.5.1, users can rollback to Samza 1.4 and keep the old start up flow using _config-path_ & _config-factory_.
+
+### Bug Fixes
+[SAMZA-2578](https://issues.apache.org/jira/browse/SAMZA-2578) Excessive trimming during transactional state restore
+
+### Sources downloads
+A source download of Samza 1.5.1 is available [here](https://dist.apache.org/repos/dist/release/samza/1.5.1/), and is also available in Apache’s Maven repository. See Samza’s download [page](https://samza.apache.org/startup/download/) for details and Samza’s feature preview for new features.
diff --git a/docs/_config.yml b/docs/_config.yml
index c62607f..48a3b15 100644
--- a/docs/_config.yml
+++ b/docs/_config.yml
@@ -25,7 +25,7 @@
 baseurl: http://samza.apache.org
 version: latest
 # this is the version you will go if you click 'switch version' in "latest" pages.
-latest-release: '1.5.0'
+latest-release: '1.5.1'
 collections:
   menu:
     output: false
diff --git a/docs/_menu/index.html b/docs/_menu/index.html
index 243bc71..6b37f76 100644
--- a/docs/_menu/index.html
+++ b/docs/_menu/index.html
@@ -12,6 +12,8 @@
     items_attributes: 'data-documentation="/learn/documentation/version/"'
   - menu_title: Releases
     items:
+      - menu_title: 1.5.1
+        url: '/releases/1.5.1'
       - menu_title: 1.5.0
         url: '/releases/1.5.0'
       - menu_title: 1.4.0
diff --git a/docs/_releases/1.5.1.md b/docs/_releases/1.5.1.md
new file mode 100644
index 0000000..1eb5efe
--- /dev/null
+++ b/docs/_releases/1.5.1.md
@@ -0,0 +1,70 @@
+---
+version: '1.5.1'
+order: 151
+layout: page
+menu_title: '1.5.1'
+title: Apache Samza 1.5.1 <a href="/learn/documentation/1.5.1/">      [Docs] </a>
+---
+<!--
+   Licensed to the Apache Software Foundation (ASF) under one or more
+   contributor license agreements.  See the NOTICE file distributed with
+   this work for additional information regarding copyright ownership.
+   The ASF licenses this file to You under the Apache License, Version 2.0
+   (the "License"); you may not use this file except in compliance with
+   the License.  You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+-->
+
+We are thrilled to announce the release of Apache Samza 1.5.1.
+
+### Bug Fixes:
+In 1.5 release, we enabled transactional state by default for all samza jobs. We identified a critical bug related to trimming the state and have addressed the issue in 1.5.1.
+For applications that are already on Samza 1.5.0, updating your dependencies to use Samza 1.5.1 should be sufficient to upgrade.
+For applications that are on version 1.4 & below, please follow the upgrade instructions below.
+
+
+### Upgrading your application to Apache Samza 1.5.0
+ConfigFactory is deprecated as Job Runner does not load full job config anymore. Instead, ConfigLoaderFactory is introduced to be executed on ClusterBasedJobCoordinator to fetch full job config.
+If you are using the default PropertiesConfigFactory, simply switching to use the default PropertiesConfigLoaderFactory will work, otherwise if you are using a custom ConfigFactory, kindly creates its new counterpart following ConfigLoaderFactory. 
+
+Configs related to job submission must be explicitly provided to Job Runner as it is no longer loading full job config anymore. These configs include
+
+* Configs directly related to job submission, such as yarn.package.path, job.name etc.
+* Configs needed by the config loader on AM to fetch job config, such as path to the property file in the tarball, all of such configs will have a job.config.loader.properties prefix.
+* Configs that users would like to override
+
+Full list of the job submission configurations can be found [here](https://cwiki.apache.org/confluence/display/SAMZA/SEP-23%3A+Simplify+Job+Runner#SEP23:SimplifyJobRunner-References)
+
+#### Usage Instructions
+Alternative way when submitting job,
+{% highlight bash %}
+deploy/samza/bin/run-app.sh
+ --config yarn.package.path=<package_path>
+ --config job.name=<job_name>
+{% endhighlight %}
+can be simplified to
+{% highlight bash %}
+deploy/samza/bin/run-app.sh
+ --config-path=/path/to/submission/properties/file/submission.properties
+{% endhighlight %}
+where submission.properties contains
+{% highlight jproperties %}
+yarn.package.path=<package_path>
+job.name=<job_name>
+{% endhighlight %}
+
+#### Rollback Instructions
+In case of a problem in Samza 1.5.1, users can rollback to Samza 1.4 and keep the old start up flow using _config-path_ & _config-factory_.
+
+### Bug Fixes
+[SAMZA-2578](https://issues.apache.org/jira/browse/SAMZA-2578) Excessive trimming during transactional state restore
+
+### Sources downloads
+A source download of Samza 1.5.1 is available [here](https://dist.apache.org/repos/dist/release/samza/1.5.1/), and is also available in Apache’s Maven repository. See Samza’s download [page](https://samza.apache.org/startup/download/) for details and Samza’s feature preview for new features.
diff --git a/docs/archive/index.html b/docs/archive/index.html
index 11fe092..fec3548 100644
--- a/docs/archive/index.html
+++ b/docs/archive/index.html
@@ -27,6 +27,14 @@
   <li><a href="../startup/hello-samza/latest">Hello Samza</a></li>
 </ul>
 
+<h4 id="1.5.1">1.5.1 Release</h4>
+
+<ul class="documentation-list">
+  <li><a href="../learn/documentation/1.5.1">Documentation</a></li>
+  <li><a href="../learn/tutorials/1.5.1">Tutorials</a></li>
+  <li><a href="../startup/hello-samza/1.5.1">Hello Samza</a></li>
+</ul>
+
 <h4 id="1.5">1.5 Release</h4>
 
 <ul class="documentation-list">
diff --git a/docs/startup/download/index.md b/docs/startup/download/index.md
index 41aa440..35d4c06 100644
--- a/docs/startup/download/index.md
+++ b/docs/startup/download/index.md
@@ -31,6 +31,7 @@
 
  Samza tools package contains command line tools that user can run to use Samza and it's input/output systems.
 
+ * [samza-tools_2.11-1.5.1.tgz](http://www-us.apache.org/dist/samza/1.5.1/samza-tools_2.11-1.5.1.tgz)
  * [samza-tools_2.11-1.5.0.tgz](http://www-us.apache.org/dist/samza/1.5.0/samza-tools_2.11-1.5.0.tgz)
  * [samza-tools_2.11-1.4.0.tgz](http://www-us.apache.org/dist/samza/1.4.0/samza-tools_2.11-1.4.0.tgz)
  * [samza-tools_2.11-1.3.1.tgz](http://www-us.apache.org/dist/samza/1.3.1/samza-tools_2.11-1.3.1.tgz)
@@ -42,6 +43,7 @@
 
 ### Source Releases
 
+ * [samza-sources-1.5.1.tgz](http://www.apache.org/dyn/closer.lua/samza/1.5.1)
  * [samza-sources-1.5.0.tgz](http://www.apache.org/dyn/closer.lua/samza/1.5.0)
  * [samza-sources-1.4.0.tgz](http://www.apache.org/dyn/closer.lua/samza/1.4.0)
  * [samza-sources-1.3.1.tgz](http://www.apache.org/dyn/closer.lua/samza/1.3.1)
@@ -75,12 +77,12 @@
 <dependency>
   <setId>org.apache.samza</setId>
   <artifactId>samza-api</artifactId>
-  <version>1.5.0</version>
+  <version>1.5.1</version>
 </dependency>
 <dependency>
   <setId>org.apache.samza</setId>
   <artifactId>samza-core_2.11</artifactId>
-  <version>1.5.0</version>
+  <version>1.5.1</version>
   <scope>runtime</scope>
 </dependency>
 <dependency>
@@ -88,37 +90,37 @@
   <artifactId>samza-shell</artifactId>
   <classifier>dist</classifier>
   <type>tgz</type>
-  <version>1.5.0</version>
+  <version>1.5.1</version>
   <scope>runtime</scope>
 </dependency>
 <dependency>
   <setId>org.apache.samza</setId>
   <artifactId>samza-yarn_2.11</artifactId>
-  <version>1.5.0</version>
+  <version>1.5.1</version>
   <scope>runtime</scope>
 </dependency>
 <dependency>
   <setId>org.apache.samza</setId>
   <artifactId>samza-kv_2.11</artifactId>
-  <version>1.5.0</version>
+  <version>1.5.1</version>
   <scope>runtime</scope>
 </dependency>
 <dependency>
   <setId>org.apache.samza</setId>
   <artifactId>samza-kv-rocksdb_2.11</artifactId>
-  <version>1.5.0</version>
+  <version>1.5.1</version>
   <scope>runtime</scope>
 </dependency>
 <dependency>
   <setId>org.apache.samza</setId>
   <artifactId>samza-kv-inmemory_2.11</artifactId>
-  <version>1.5.0</version>
+  <version>1.5.1</version>
   <scope>runtime</scope>
 </dependency>
 <dependency>
   <setId>org.apache.samza</setId>
   <artifactId>samza-kafka_2.11</artifactId>
-  <version>1.5.0</version>
+  <version>1.5.1</version>
   <scope>runtime</scope>
 </dependency>
 {% endhighlight %}