add change log

Signed-off-by: zhichao-aws <zhichaog@amazon.com>

CHANGELOG.md

@@ -11,6 +11,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fixed exception for case when Hybrid query being wrapped into bool query ([#490](https://github.com/opensearch-project/neural-search/pull/490))
 - Hybrid query and nested type fields ([#498](https://github.com/opensearch-project/neural-search/pull/498))
 - 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))
 ### Infrastructure
 ### Documentation
 ### Maintenance