add atomicdex

Author: ca333

README.md

@@ -152,6 +152,8 @@
 - [Anchor](https://github.com/coral-xyz/anchor)
   is a framework for Solana's Sealevel runtime providing several convenient developer tools for writing smart contracts.
 ## Cross-Chain
+- [AtomicDEX](https://atomicdex.io).
+  Cross-chain and cross-protocol p2p orderbook based decentralized exchange and interoperability bridge (self-custodial).
 - [Comit](https://comit.network/) is an open protocol facilitating
   trustless cross-blockchain applications.
 - [IBC](https://github.com/informalsystems/ibc-rs).