Added changelog

Signed-off-by: Nils Bandener <nils.bandener@eliatra.com>

Author: nibix

CHANGELOG.md

@@ -14,6 +14,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Add pluggable gRPC interceptors with explicit ordering([#19005](https://github.com/opensearch-project/OpenSearch/pull/19005))
 - Add metrics for the merged segment warmer feature ([#18929](https://github.com/opensearch-project/OpenSearch/pull/18929))
 - Add pointer based lag metric in pull-based ingestion ([#19635](https://github.com/opensearch-project/OpenSearch/pull/19635))
+- Introduced internal API for retrieving metadata about requested indices from transport actions  ([#18523](https://github.com/opensearch-project/OpenSearch/pull/18523))
 
 ### Changed
 - Faster `terms` query creation for `keyword` field with index and docValues enabled ([#19350](https://github.com/opensearch-project/OpenSearch/pull/19350))