Added changelog entry

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

Author: nibix

CHANGELOG.md

@@ -15,6 +15,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Add a dynamic setting to change skip_cache_factor and min_frequency for querycache ([#18351](https://github.com/opensearch-project/OpenSearch/issues/18351))
 - Add overload constructor for Translog to accept Channel Factory as a parameter ([#18918](https://github.com/opensearch-project/OpenSearch/pull/18918))
 - Add subdirectory-aware store module with recovery support ([#19132](https://github.com/opensearch-project/OpenSearch/pull/19132))
+- Introduced internal API for retrieving metadata about requested indices from transport actions  ([#18523](https://github.com/opensearch-project/OpenSearch/pull/18523))
 
 ### Changed
 - Add CompletionStage variants to methods in the Client Interface and default to ActionListener impl ([#18998](https://github.com/opensearch-project/OpenSearch/pull/18998))