Add a few more release notes for 0.9.0

Change-Id: Ibbd66838b51e467d4c4808fa09972d0cba717143
Reviewed-on: http://gerrit.cloudera.org:8080/3273
Tested-by: Kudu Jenkins
Reviewed-by: Misty Stanley-Jones <misty@apache.org>
(cherry picked from commit 0e9fd8c155e895af0c652267575c88b55172ce9e)
Reviewed-on: http://gerrit.cloudera.org:8080/3276
Reviewed-by: Jean-Daniel Cryans
Tested-by: Jean-Daniel Cryans
diff --git a/docs/release_notes.adoc b/docs/release_notes.adoc
index e912455..f88ecb6 100644
--- a/docs/release_notes.adoc
+++ b/docs/release_notes.adoc
@@ -97,6 +97,28 @@
 - link:http://gerrit.cloudera.org:8080/#/c/2992/[Gerrit 2992] Added the ability
   to update and insert from Spark using a Kudu datasource.
 
+[[rn_0.9.0_improvements]]
+==== Improvements
+
+- link:https://issues.apache.org/jira/browse/KUDU-1415[KUDU-1415] Added statistics in the Java
+  client such as the number of bytes written and the number of operations applied.
+
+- link:https://issues.apache.org/jira/browse/KUDU-1451[KUDU-1451] Improved tablet server restart
+  time when the tablet server needs to clean up of a lot previously deleted tablets. Tablets are
+  now cleaned up after they are deleted.
+
+[[rn_0.9.0_fixed_issues]]
+==== Fixed Issues
+
+- link:https://issues.apache.org/jira/browse/KUDU-678[KUDU-678] Fixed a leak that happened during
+  DiskRowSet compactions where tiny blocks were still written to disk even if there were no REDO
+  records. With the default block manager, it usually resulted in block containers with thousands
+  of tiny blocks.
+
+- link:https://issues.apache.org/jira/browse/KUDU-1437[KUDU-1437] Fixed a data corruption issue
+  that occured after compacting sequences of negative INT32 values in a column that
+  was configured with RLE encoding.
+
 [[rn_0.9.0_changes]]
 ==== Other noteworthy changes