Add a changelog entry

Signed-off-by: Michael Froh <[email protected]>

Author: msfroh

CHANGELOG.md

@@ -95,6 +95,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fix Shallow copy snapshot failures on closed index ([#16868](https://github.com/opensearch-project/OpenSearch/pull/16868))
 - Fix multi-value sort for unsigned long ([#16732](https://github.com/opensearch-project/OpenSearch/pull/16732))
 - The `phone-search` analyzer no longer emits the tel/sip prefix, international calling code, extension numbers and unformatted input as a token ([#16993](https://github.com/opensearch-project/OpenSearch/pull/16993))
+- Stop processing search requests when _msearch request is cancelled ([#17005](https://github.com/opensearch-project/OpenSearch/pull/17005))
 
 ### Security