Add changelog

Signed-off-by: Vinay Krishna Pudyodu <vinkrish.neo@gmail.com>

Author: vinaykpud

CHANGELOG.md

@@ -21,6 +21,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Add support for non-timing info in profiler ([#18460](https://github.com/opensearch-project/OpenSearch/issues/18460))
 - Extend Approximation Framework to other numeric types ([#18530](https://github.com/opensearch-project/OpenSearch/issues/18530))
 - Add Semantic Version field type mapper and extensive unit tests([#18454](https://github.com/opensearch-project/OpenSearch/pull/18454))
+- Optimization in Numeric Terms Aggregation query for Large Bucket Counts([#18702](https://github.com/opensearch-project/OpenSearch/pull/18702))
 
 ### Changed
 - Update Subject interface to use CheckedRunnable ([#18570](https://github.com/opensearch-project/OpenSearch/issues/18570))