Update Docker documentation (#120)

Co-authored-by: Eamon Ford <eamon.d.ford@jpl.nasa.gov>
diff --git a/docker/Readme.rst b/docker/Readme.rst
deleted file mode 100644
index a305620..0000000
--- a/docker/Readme.rst
+++ /dev/null
@@ -1 +0,0 @@
-# NEXUS Docker
diff --git a/docker/nexus-imaging/Dockerfile b/docker/nexus-imaging/Dockerfile
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index b6e28c1..0000000
--- a/docker/nexus-imaging/Dockerfile
+++ /dev/null
@@ -1,25 +0,0 @@
-# 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.
-ARG tag_version=1.0.0-SNAPSHOT
-FROM sdap/nexus-webapp:${tag_version}
-
-MAINTAINER Apache SDAP "dev@sdap.apache.org"
-
-RUN yum -y install unzip aws-cli
-
-COPY docker-entrypoint.sh /tmp/docker-entrypoint.sh
-
-WORKDIR /tmp
-ENTRYPOINT ["/tmp/docker-entrypoint.sh"]
diff --git a/docker/nexus-imaging/docker-entrypoint.sh b/docker/nexus-imaging/docker-entrypoint.sh
deleted file mode 100755
index 638be1c..0000000
--- a/docker/nexus-imaging/docker-entrypoint.sh
+++ /dev/null
@@ -1,19 +0,0 @@
-#!/bin/bash
-
-# 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.
-
-cd ${NEXUS_SRC}/analysis/webservice
-python WorkflowDriver.py --ds ${DATASET_NAME} --g ${GRANULE_NAME} --p ${PREFIX} --ct ${COLOR_TABLE} --min ${MIN} --max ${MAX} --h ${HEIGHT} --w ${WIDTH} --t ${TIME_INTERVAL} --i ${INTERP}
diff --git a/docker/nexus-webapp/Readme.md b/docker/nexus-webapp/Readme.md
index 7aeb962..788582d 100644
--- a/docker/nexus-webapp/Readme.md
+++ b/docker/nexus-webapp/Readme.md
@@ -1,41 +1,25 @@
 
-# How to Build
+# Build the image
 
-All docker builds should happen from this directory. For copy/paste ability, first export the environment variable `BUILD_VERSION` to the version number you would like to tag images as.
-
-## spark-mesos-base
-
-    docker build -t sdap/spark-mesos-base:${BUILD_VERSION} -f mesos/base/Dockerfile .
-
-## spark-mesos-master
-
-Builds from `spark-mesos-base` and supports `tag_version` build argument which specifies the version of base to build from.
-
-    docker build -t sdap/spark-mesos-master:${BUILD_VERSION} -f mesos/master/Dockerfile .
-
-## spark-mesos-agent
-
-Builds from `spark-mesos-base` and supports `tag_version` build argument which specifies the version of base to build from.
-
-    docker build -t sdap/spark-mesos-agent:${BUILD_VERSION} -f mesos/agent/Dockerfile .
-
-## nexus-webapp:mesos
-
-Builds from `spark-mesos-base` and supports `tag_version` build argument which specifies the version of base to build from.
-
-    docker build -t sdap/nexus-webapp:mesos.${BUILD_VERSION} -f mesos/webapp/Dockerfile .
-
-## nexus-webapp:standalone
-
-    docker build -t sdap/nexus-webapp:standalone.${BUILD_VERSION} -f standalone/Dockerfile .
-
-# Push Images
-
-Push the images to the `sdap` organization on DockerHub
-
-    docker push sdap/spark-mesos-base:${BUILD_VERSION}
-    docker push sdap/spark-mesos-master:${BUILD_VERSION}
-    docker push sdap/spark-mesos-agent:${BUILD_VERSION}
-    docker push sdap/nexus-webapp:mesos.${BUILD_VERSION}
-    docker push sdap/nexus-webapp:standalone.${BUILD_VERSION}
+To build the nexus-webapp docker image, `cd` into the root directory of this project (`incubator-sdap-nexus/`) and run:
     
+     docker build . -f docker/nexus-webapp/Dockerfile -t nexusjpl/nexus-webapp:distributed.${BUILD_VERSION}
+
+where `${BUILD_VERSION}` is the build version of SDAP.
+
+
+# Push the image
+
+Push the images to the `nexusjpl` organization on DockerHub
+
+    docker push nexusjpl/nexus-webapp:distributed.${BUILD_VERSION}
+
+# Add a new tag to the Git repo
+
+When you push a new image that is intended for more than just private use, you should also `git tag` the commit from which
+the image was built. The tag name should be the docker image tag of the new image you pushed, i.e.:
+
+    git tag distributed.0.3.0
+    git push --tags
+
+You can see a list of all SDAP version tags on the [SDAP Git repo tags page](https://github.com/apache/incubator-sdap-nexus/tags).
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