Add release notes (opensearch-project#363) (opensearch-project#364)

Signed-off-by: Ashish Agrawal <ashisagr@amazon.com>
(cherry picked from commit 1ca639f)

Co-authored-by: Ashish Agrawal <ashisagr@amazon.com>
Signed-off-by: AWSHurneyt <hurneyt@amazon.com>

Author: 2 people

release-notes/opensearch-common-utils.release-notes-2.6.0.0.md

@@ -0,0 +1,15 @@
+## Version 2.6.0.0 2023-02-21
+
+Compatible with OpenSearch 2.6.0
+
+### Maintenance
+* Increment version to 2.6.0-SNAPSHOT ([#344](https://github.com/opensearch-project/common-utils/pull/344))
+
+### Refactoring
+* Add a super admin client builder w/ hosts params ([#322](https://github.com/opensearch-project/common-utils/pull/322))
+
+### Bug Fixes
+* Fix streaming functions for LegacySNSMessage ([#324](https://github.com/opensearch-project/common-utils/pull/324))
+
+### Documentation
+* Added 2.6 release notes. ([#363](https://github.com/opensearch-project/common-utils/pull/363))