remove outdated info (#117)

Author: jakub-tldr

README.md

@@ -9,7 +9,7 @@ instructions.
 
 ## Community and Support
 
-Find us on Matrix: [#defguard:teonite.com](https://matrix.to/#/#defguard:teonite.com)
+Reach out to our community via [GitHub Discussions](https://github.com/DefGuard/defguard/discussions/new/choose)
 
 ## Contribution