Update HISTORY.md for 7.2 release (facebook#9848)

Summary: Pull Request resolved: facebook#9848

Reviewed By: riversand963

Differential Revision: D35677606

Pulled By: jay-zhuang

fbshipit-source-id: 8a597ea47f302a6f51fb6672a33c848d613bccfc

HISTORY.md

@@ -1,5 +1,5 @@
 # Rocksdb Change Log
-## Unreleased
+## 7.2.0 (04/15/2022)
 ### Bug Fixes
 * Fixed bug which caused rocksdb failure in the situation when rocksdb was accessible using UNC path
 * Fixed a race condition when 2PC is disabled and WAL tracking in the MANIFEST is enabled. The race condition is between two background flush threads trying to install flush results, causing a WAL deletion not tracked in the MANIFEST. A future DB open may fail.