update change log

Signed-off-by: yuye-aws <[email protected]>

CHANGELOG.md

@@ -11,6 +11,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fix typo for sparse encoding processor factory([#578](https://github.com/opensearch-project/neural-search/pull/578))
 - Add non-null check for queryBuilder in NeuralQueryEnricherProcessor ([#615](https://github.com/opensearch-project/neural-search/pull/615))
 - Add max_token_score field placeholder in NeuralSparseQueryBuilder to fix the rolling-upgrade from 2.x nodes bwc tests. ([#696](https://github.com/opensearch-project/neural-search/pull/696))
+- Bug test for other BWC tests
 ### Infrastructure
 - Adding integration tests for scenario of hybrid query with aggregations ([#632](https://github.com/opensearch-project/neural-search/pull/632))
 ### Documentation