Mention the new MultiGetEntity API in HISTORY.md (#11226)

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/11226

Reviewed By: akankshamahajan15

Differential Revision: D43317602

Pulled By: ltamasi

fbshipit-source-id: 4b7e063848d3cfbdb9f0c0f54d68aeab8a82595c

HISTORY.md

@@ -32,6 +32,7 @@
 
 ### New Features
 * Compaction filters are now supported for wide-column entities by means of the `FilterV3` API. See the comment of the API for more details.
+* Added a new `MultiGetEntity` API that enables batched wide-column point lookups. See the API comments for more details.
 
 ## 7.10.0 (01/23/2023)
 ### Behavior changes