docs: Add matrix room to README.md

README.md

@@ -8,3 +8,5 @@ This is the monorepo containing the source code for all of our core projects:
 - and other crates we use in our binaries
 
 If you're just here for the software, head over to the [releases](https://github.com/UnstoppableSwap/xmr-btc-swap/releases/latest) tab and grab the binary for your operating system! If you're just looking for documentation, check out our [docs page](https://docs.unstoppableswap.net/) or our [github docs](docs/README.md).
+
+Join our [Matrix room](https://matrix.to/#/#unstoppableswap-core:matrix.org) to follow development more closely.