Update USERS.md
Update USERS.md

Summary: Closes https://github.com/facebook/rocksdb/pull/1629

Differential Revision: D4293183

Pulled By: IslamAbdelRahman

fbshipit-source-id: 759ea92

wat-ze-hex/rocksdb,vmx/rocksdb,wat-ze-hex/rocksdb,SunguckLee/RocksDB,SunguckLee/RocksDB,Andymic/rocksdb,wat-ze-hex/rocksdb,vmx/rocksdb,vmx/rocksdb,SunguckLee/RocksDB,SunguckLee/RocksDB,vmx/rocksdb,wat-ze-hex/rocksdb,bbiao/rocksdb,bbiao/rocksdb,Andymic/rocksdb,bbiao/rocksdb,Andymic/rocksdb,bbiao/rocksdb,bbiao/rocksdb,bbiao/rocksdb,bbiao/rocksdb,SunguckLee/RocksDB,wat-ze-hex/rocksdb,Andymic/rocksdb,Andymic/rocksdb,wat-ze-hex/rocksdb,Andymic/rocksdb,wat-ze-hex/rocksdb,SunguckLee/RocksDB,vmx/rocksdb,vmx/rocksdb,bbiao/rocksdb,vmx/rocksdb,SunguckLee/RocksDB,wat-ze-hex/rocksdb,SunguckLee/RocksDB,vmx/rocksdb,Andymic/rocksdb,Andymic/rocksdb