Remove 'experimental' comment around level_compaction_dynamic_level_bytes option
Remove 'experimental' comment around level_compaction_dynamic_level_bytes option

Summary:
Remove misleading 'experimental' comment around `level_compaction_dynamic_level_bytes` option. This is not experimental anymore and is ready for wider adoption. MyRocks is already using it in production.
Closes https://github.com/facebook/rocksdb/pull/2878

Differential Revision: D5828890

Pulled By: sagar0

fbshipit-source-id: fffb45f4999f689b7eca326e4f4caf472d40c5a9

Andymic/rocksdb,SunguckLee/RocksDB,SunguckLee/RocksDB,Andymic/rocksdb,bbiao/rocksdb,Andymic/rocksdb,bbiao/rocksdb,bbiao/rocksdb,SunguckLee/RocksDB,Andymic/rocksdb,bbiao/rocksdb,Andymic/rocksdb,SunguckLee/RocksDB,bbiao/rocksdb,SunguckLee/RocksDB,SunguckLee/RocksDB,SunguckLee/RocksDB,Andymic/rocksdb,Andymic/rocksdb,bbiao/rocksdb,SunguckLee/RocksDB,Andymic/rocksdb,bbiao/rocksdb,bbiao/rocksdb