Add bug fix to HISTORY.md (#10091)

Summary:
Add to HISTORY.md the bug fixed in https://github.com/facebook/rocksdb/issues/10051

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10091

Reviewed By: ajkr

Differential Revision: D36821861

Pulled By: cbi42

fbshipit-source-id: 598812fab88f65c0147ece53cff55cf4ea73aac6

HISTORY.md

@@ -1,5 +1,7 @@
 # Rocksdb Change Log
 ## Unreleased
+### Bug Fixes
+* Fixed a bug where a snapshot taken during SST file ingestion would be unstable.
 ### Public API changes
 * Add new API GetUnixTime in Snapshot class which returns the unix time at which Snapshot is taken.
 * Add transaction `get_pinned` and `multi_get` to C API.