Mention PR 8605 in HISTORY.md (#8619)

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/8619

Reviewed By: riversand963

Differential Revision: D30081937

Pulled By: ltamasi

fbshipit-source-id: 57505957ae2c22d4b194aa28cb3fd261b3b39919

HISTORY.md

@@ -2,6 +2,8 @@
 ## Unreleased
 ### Bug Fixes
 * If the primary's CURRENT file is missing or inaccessible, the secondary instance should not hang repeatedly trying to switch to a new MANIFEST. It should instead return the error code encountered while accessing the file.
+* Fixed a race related to the destruction of `ColumnFamilyData` objects. The earlier logic unlocked the DB mutex before destroying the thread-local `SuperVersion` pointers, which could result in a process crash if another thread managed to get a reference to the `ColumnFamilyData` object.
+
 ### New Features
 * Made the EventListener extend the Customizable class.
 * EventListeners that have a non-empty Name() and that are registered with the ObjectRegistry can now be serialized to/from the OPTIONS file.