Add release notes for 0.9 release

Author: dai-chen

opendistro-elasticsearch-sql.release-notes

@@ -1,9 +1,17 @@
 
-## 2019-04-02, Version 0.8.0 (Current)
+## 2019-04-19, Version 0.9.0 (Current)
 
 ### Notable Changes
 
-* Feature [#12](https://github.com/opendistro-for-elasticsearch/sql/issues/12): Add support for Elasticsearch 6.6
+* Feature [#29](https://github.com/opendistro-for-elasticsearch/sql/issues/29): Add support for Elasticsearch 6.7.1
+* Migration [#17](https://github.com/opendistro-for-elasticsearch/sql/issues/17): Migrate legacy integration tests in Maven to ES test in Gradle.
+
+
+## 2019-04-02, Version 0.8.0
+
+### Notable Changes
+
+* Feature [#12](https://github.com/opendistro-for-elasticsearch/sql/issues/12): Add support for Elasticsearch 6.6.2
 * Bug fix [#9](https://github.com/opendistro-for-elasticsearch/sql/issues/9): Fix issue for query by index pattern in JDBC driver.
 * Bug fix [#10](https://github.com/opendistro-for-elasticsearch/sql/issues/10): Return friendly error message instead of NPE for illegal query and other exception cases.