Add to CHANGELOG

Signed-off-by: Craig Perkins <[email protected]>

Author: cwperks

CHANGELOG.md

@@ -129,6 +129,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 ### Deprecated
 
 ### Removed
+- Remove handling of index.mapper.dynamic in AutoCreateIndex([#13067](https://github.com/opensearch-project/OpenSearch/pull/13067))
 
 ### Fixed
 - Fix bulk API ignores ingest pipeline for upsert ([#12883](https://github.com/opensearch-project/OpenSearch/pull/12883))