Fix history to not include some features in 6.1 (#5224)

Summary:
Fix HISTORY.md by removing a few items from 6.1.1 history as they did not make into the 6.1.fb branch.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5224

Differential Revision: D15017030

Pulled By: sagar0

fbshipit-source-id: 090724d326d29168952e06dc1a5090c03fdd739e

HISTORY.md

@@ -1,29 +1,29 @@
 # Rocksdb Change Log
 
-### Unreleased
+## Unreleased
 ### New Features
 * Improve range scan performance by avoiding per-key upper bound check in BlockBasedTableIterator.
+* Introduce Periodic Compaction for Level style compaction. Files are re-compacted periodically and put in the same level.
 
 ### Public API Change
+* Change the behavior of OptimizeForPointLookup(): move away from hash-based block-based-table index, and use whole key memtable filtering.
+* Change the behavior of OptimizeForSmallDb(): use a 16MB block cache, put index and filter blocks into it, and cost the memtable size to it. DBOptions.OptimizeForSmallDb() and ColumnFamilyOptions.OptimizeForSmallDb() start to take an optional cache object.
 * Added BottommostLevelCompaction::kForceOptimized to avoid double compacting newly compacted files in bottom level compaction of manual compaction.
 
 ### Bug Fixes
 * Adjust WriteBufferManager's dummy entry size to block cache from 1MB to 256KB.
+* Fix a race condition between WritePrepared::Get and ::Put with duplicate keys.
+* Fix crash when memtable prefix bloom is enabled and read/write a key out of domain of prefix extractor.
 
 ## 6.1.1 (4/9/2019)
 ### New Features
 * When reading from option file/string/map, customized comparators and/or merge operators can be filled according to object registry.
-* Introduce Periodic Compaction for Level style compaction. Files are re-compacted periodically and put in the same level.
 
 ### Public API Change
-* Change the behavior of OptimizeForPointLookup(): move away from hash-based block-based-table index, and use whole key memtable filtering.
-* Change the behavior of OptimizeForSmallDb(): use a 16MB block cache, put index and filter blocks into it, and cost the memtable size to it. DBOptions.OptimizeForSmallDb() and ColumnFamilyOptions.OptimizeForSmallDb() start to take an optional cache object.
 
 ### Bug Fixes
 * Fix a bug in 2PC where a sequence of txn prepare, memtable flush, and crash could result in losing the prepared transaction.
 * Fix a bug in Encryption Env which could cause encrypted files to be read beyond file boundaries.
-* Fix a race condition between WritePrepared::Get and ::Put with duplicate keys.
-* Fix crash when memtable prefix bloom is enabled and read/write a key out of domain of prefix extractor.
 
 ## 6.1.0 (3/27/2019)
 ### New Features