Merge pull request #581 from vladb38/patch-3

Update USERS.md

USERS.md

@@ -28,4 +28,6 @@ You can learn more from this great blog post by Mike Lin: http://devblog.dnanexu
 Iron.io is using RocksDB as a storage engine for their distributed queueing system.
 Learn more from Tech Talk by Reed Allman: http://www.youtube.com/watch?v=HTjt6oj-RL4
 
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+# Turn
+Turn is using RocksDB as a storage layer for their key/value store, serving at peak 2.4MM QPS out of different datacenters.
+Check out our RocksDB Protobuf merge operator at: https://github.com/vladb38/rocksdb_protobuf