Add avrio to USERS.md (facebook#5748)

Summary:
Add Avrio's use case of RocksDB to USERS.md
Pull Request resolved: facebook#5748

Differential Revision: D17392483

Pulled By: riversand963

fbshipit-source-id: 673f4e1a5c82079ec8dfb2816db0cc9af9d38341

USERS.md

@@ -97,5 +97,8 @@ LzLabs is using RocksDB as a storage engine in their multi-database distributed
 ## IOTA Foundation
  [IOTA Foundation](https://www.iota.org/) is using RocksDB in the [IOTA Reference Implementation (IRI)](https://github.com/iotaledger/iri) to store the local state of the Tangle. The Tangle is the first open-source distributed ledger powering the future of the Internet of Things.
 
+## Avrio Project
+ [Avrio Project](http://avrio-project.github.io/avrio.network/) is using RocksDB in [Avrio ](https://github.com/avrio-project/avrio) to store blocks, account balances and data and other blockchain-releated data. Avrio is a multiblockchain decentralized cryptocurrency empowering monetary transactions.
+
 ## Crux
 [Crux](https://github.com/juxt/crux) is a document database that uses RocksDB for local [EAV](https://en.wikipedia.org/wiki/Entity%E2%80%93attribute%E2%80%93value_model) index storage to enable point-in-time bitemporal Datalog queries. The "unbundled" architecture uses Kafka to provide horizontal scalability.