DOC: Add link to matrix community

README.md

@@ -35,7 +35,9 @@ when creating the merge request. This allows our team to work with you on your r
 - If you have a suggestion for the [documentation](https://docs.indiscale.com/caosdb-pylib/), 
 the preferred way is also a merge request as describe above (the documentation resides in `src/doc`).
 However, you can also create an issue for it. 
-- You can also contact us at **info (AT) caosdb.de**.
+- You can also contact us at **info (AT) caosdb.de** and join the
+  CaosDB community on
+  [#caosdb:matrix.org](https://matrix.to/#/!unwwlTfOznjEnMMXxf:matrix.org).
 
 ## License