Fix HISTORY.md for #8518 (#8594)

Summary:
PR https://github.com/facebook/rocksdb/issues/8518 merge the change to wrong section.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8594

Reviewed By: riversand963

Differential Revision: D29974565

Pulled By: jay-zhuang

fbshipit-source-id: 51c930d93fbdb406fe31ff73c96548a6f88b9965

HISTORY.md

@@ -5,6 +5,10 @@
 ### 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.
+
+### Performance Improvements
+* Try to avoid updating DBOptions if `SetDBOptions()` does not change any option value.
+
 ## 6.23.0 (2021-07-16)
 ### Behavior Changes
 * Obsolete keys in the bottommost level that were preserved for a snapshot will now be cleaned upon snapshot release in all cases. This form of compaction (snapshot release triggered compaction) previously had an artificial limitation that multiple tombstones needed to be present.
@@ -28,9 +32,6 @@
 * Added APIs to the Customizable class to allow developers to create their own Customizable classes.  Created the utilities/customizable_util.h file to contain helper methods for developing new Customizable classes.
 * Change signature of SecondaryCache::Name().  Make SecondaryCache customizable and add SecondaryCache::CreateFromString method.
 
-### Performance Improvements
-* Try to avoid updating DBOptions if `SetDBOptions()` does not change any option value.
-
 ## 6.22.0 (2021-06-18)
 ### Behavior Changes
 * Added two additional tickers, MEMTABLE_PAYLOAD_BYTES_AT_FLUSH and MEMTABLE_GARBAGE_BYTES_AT_FLUSH. These stats can be used to estimate the ratio of "garbage" (outdated) bytes in the memtable that are discarded at flush time.