add change log

Signed-off-by: bowenlan-amzn <[email protected]>

CHANGELOG.md

@@ -173,6 +173,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Performance improvement for MultiTerm Queries on Keyword fields ([#7057](https://github.com/opensearch-project/OpenSearch/issues/7057))
 - Refactor common parts from the Rounding class into a separate 'round' package ([#11023](https://github.com/opensearch-project/OpenSearch/issues/11023))
 - Performance improvement for date histogram aggregations without sub-aggregations ([#11083](https://github.com/opensearch-project/OpenSearch/pull/11083))
+- Apply the fast filter optimization to composite aggregation ([#11505](https://github.com/opensearch-project/OpenSearch/pull/11083))
 - Disable concurrent aggs for Diversified Sampler and Sampler aggs ([#11087](https://github.com/opensearch-project/OpenSearch/issues/11087))
 - Made leader/follower check timeout setting dynamic ([#10528](https://github.com/opensearch-project/OpenSearch/pull/10528))
 - Change error message when per shard document limit is breached ([#11312](https://github.com/opensearch-project/OpenSearch/pull/11312))