add changelog

Signed-off-by: gesong.samuel <[email protected]>

CHANGELOG.md

@@ -117,7 +117,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fix null values indexed as "null" strings in flat_object field ([#14069](https://github.com/opensearch-project/OpenSearch/pull/14069))
 - Fix terms query on wildcard field returns nothing ([#15607](https://github.com/opensearch-project/OpenSearch/pull/15607))
 - Fix remote snapshot file_cache exceeding capacity ([#15077](https://github.com/opensearch-project/OpenSearch/pull/15077))
-
+- Fix case_insensitive query on wildcard field ([#15882](https://github.com/opensearch-project/OpenSearch/pull/15882))
 ### Security
 
 [Unreleased 2.x]: https://github.com/opensearch-project/OpenSearch/compare/2.15...2.x