add change log

Signed-off-by: zane-neo <zaniu@amazon.com>

Author: zane-neo

CHANGELOG.md

@@ -17,6 +17,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 ## [Unreleased 2.x](https://github.com/opensearch-project/neural-search/compare/2.18...2.x)
 ### Features
 ### Enhancements
+- Support different embedding types in model's response ([#1007](https://github.com/opensearch-project/neural-search/pull/1007))
 ### Bug Fixes
 -  Address inconsistent scoring in hybrid query results ([#998](https://github.com/opensearch-project/neural-search/pull/998))
 ### Infrastructure