docs: Matrix chat on home page + self-serve federated MXID in getting-started

README.md

@@ -20,6 +20,7 @@ funded through our [Open Collective](https://opencollective.com/inference-cooper
 
 - **Website:** https://inference.coop
 - **AI Chat:** https://chat.inference.coop
+- **Matrix chat:** https://matrix.inference.coop
 - **Member Dashboard:** https://dashboard.inference.coop
 - **Governance forum:** https://forum.inference.coop
 - **Source code:** https://git.inference.coop