README: Add starcoin to rust-libp2p users (#2246)

Co-authored-by: Max Inden <mail@max-inden.de>

Author: jolestar

README.md

@@ -80,3 +80,4 @@ Conduct](https://github.com/ipfs/community/blob/master/code-of-conduct.md).
 - https://github.com/ChainSafe/forest
 - https://github.com/ipfs-rust/ipfs-embed
 - https://www.actyx.com/developers/
+- https://github.com/starcoinorg/starcoin