Added 2.9 release notes. (#851)

* Added 2.9 release notes.

Signed-off-by: AWSHurneyt <hurneyt@amazon.com>

* Added 2.9 release notes.

Signed-off-by: AWSHurneyt <hurneyt@amazon.com>

* Added 2.9 release notes.

Signed-off-by: AWSHurneyt <hurneyt@amazon.com>

---------

Signed-off-by: AWSHurneyt <hurneyt@amazon.com>
(cherry picked from commit 6610f82)
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

release-notes/opensearch-index-management.release-notes-2.9.0.0.md

@@ -0,0 +1,21 @@
+## Version 2.9.0.0 2023-07-11
+
+Compatible with OpenSearch 2.9.0
+
+### Maintenance
+* Increment version to 2.9.0-SNAPSHOT. ([#805](https://github.com/opensearch-project/index-management/pull/805))
+* Added to CODEOWNERS and MAINTAINERS files. ([#810](https://github.com/opensearch-project/index-management/pull/810))
+* Upgrade httpcomponent version after OpenSearch core's upgrade. ([#847](https://github.com/opensearch-project/index-management/pull/847))
+
+### Features
+* Support for system index interface. ([#789](https://github.com/opensearch-project/index-management/pull/789))
+
+### Bug fixes
+* Bugfix/202 transform date add date conversion. ([#622](https://github.com/opensearch-project/index-management/pull/622))
+* Fix build errors after refactoring of Strings class in core. ([#786](https://github.com/opensearch-project/index-management/pull/786))
+* Fix LRON concurrent indexing throw ResourceAlreadyExists. ([#831](https://github.com/opensearch-project/index-management/pull/831))
+* ImmutableOpenMap to j.u.Map. ([#838](https://github.com/opensearch-project/index-management/pull/838))
+* Remove runtime notification settings. ([#839](https://github.com/opensearch-project/index-management/pull/839))
+
+### Documentation
+* Added 2.9 release notes. ([#851](https://github.com/opensearch-project/index-management/pull/851))