Update HISTORY (#7158)

Summary:
Mention the MultiRead bug in HISTORY.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7158

Test Plan: N/A

Reviewed By: siying

Differential Revision: D22670565

Pulled By: cheng-chang

fbshipit-source-id: 16abf0192957be66511f6a08e00157bfd37b189f

HISTORY.md

@@ -17,6 +17,7 @@
 * Disable file deletion after MANIFEST write/sync failure until db re-open or Resume() so that subsequent re-open will not see MANIFEST referencing deleted SSTs.
 * Fix a bug when index_type == kTwoLevelIndexSearch in PartitionedIndexBuilder to update FlushPolicy to point to internal key partitioner when it changes from user-key mode to internal-key mode in index partition.
 * Make compaction report InternalKey corruption while iterating over the input.
+* Fix a bug which may cause MultiGet to be slow because it may read more data than requested, but this won't affect correctness. The bug was introduced in 6.10 release.
 
 ### Public API Change
 * `DB::GetDbSessionId(std::string& session_id)` is added. `session_id` stores a unique identifier that gets reset every time the DB is opened. This DB session ID should be unique among all open DB instances on all hosts, and should be unique among re-openings of the same or other DBs. This identifier is recorded in the LOG file on the line starting with "DB Session ID:".