Update HISTORY.md for 5.0 branch

Summary:
These changes are included in the new branch-cut.
Closes https://github.com/facebook/rocksdb/pull/1621

Differential Revision: D4281015

Pulled By: yiwu-arbug

fbshipit-source-id: d88858b

HISTORY.md

 # Rocksdb Change Log
 ## Unreleased
 ### Public API Change
-* Options.level0_stop_writes_trigger default value changes from 24 to 32.
-* New compaction filter API: CompactionFilter::FilterV2(). Allows to drop ranges of keys.
-* Removed flashcache support.
 * Support dynamically change `delete_obsolete_files_period_micros` option via SetDBOptions().
 
 ## 5.0.0 (11/17/2016)
@@ -14,6 +11,9 @@
 * Support dynamically change `delayed_write_rate` option via SetDBOptions().
 * Options::allow_concurrent_memtable_write and Options::enable_write_thread_adaptive_yield are now true by default.
 * Remove Tickers::SEQUENCE_NUMBER to avoid confusion if statistics object is shared among RocksDB instance. Alternatively DB::GetLatestSequenceNumber() can be used to get the same value.
+* Options.level0_stop_writes_trigger default value changes from 24 to 32.
+* New compaction filter API: CompactionFilter::FilterV2(). Allows to drop ranges of keys.
+* Removed flashcache support.
 
 ### New Features
 * Add avoid_flush_during_shutdown option, which speeds up DB shutdown by not flushing unpersisted data (i.e. with disableWAL = true). Unpersisted data will be lost. The options is dynamically changeable via SetDBOptions().