Add rbtc to awsome-rust (#636)

README.md

@@ -148,6 +148,7 @@ See also [Rust — Production](https://www.rust-lang.org/production)(organizatio
 * [Nervos CKB](https://github.com/nervosnetwork/ckb) - Nervos CKB is a public permissionless blockchain, the common knowledge layer of Nervos network.
 * [ChainX](https://github.com/chainx-org/ChainX) - Fully Decentralized Interchain Crypto Asset Management on Polkadot.
 * [hdwallet](https://github.com/jjyr/hdwallet) - BIP-32 HD wallet related key derivation utilities.
+* [rbtc](https://github.com/lucawen/rbtc) - Convert BTC to any currency and vice-versa. [<img src="https://api.travis-ci.com/lucawen/rbtc.svg?branch=master">](https://travis-ci.com/lucawen/rbtc/)
 
 ### Database