add release notes for 1.3.15 (#2536)

Signed-off-by: Sean Kao <[email protected]>

Author: seankao31

release-notes/opensearch-sql.release-notes-1.3.15.0.md

@@ -0,0 +1,9 @@
+### Version 1.3.15.0 Release Notes
+
+Compatible with OpenSearch and OpenSearch Dashboards Version 1.3.15
+
+### Maintenance
+* Increment version to 1.3.15-SNAPSHOT ([#2457](https://github.com/opensearch-project/sql/pull/2457))
+
+### Bug Fixes
+* Bump json and wiremock version to fix CVEs ([#2533](https://github.com/opensearch-project/sql/pull/2533))