Mention contributing.md in readme

 README.md | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 75e9974..ce7b0d1 100644
--- a/README.md
+++ b/README.md
@@ -42,7 +42,9 @@ Check out the [roadmap](https://github.com/ifreund/river/issues/1)
 if you'd like to see what has been done and what is left to do.
 
 If you are interested in the development of river, please join our
-matrix channel: [#river](https://matrix.to/#/#river:matrix.org).
+matrix channel: [#river:matrix.org](https://matrix.to/#/#river:matrix.org).
+You should also read [CONTRIBUTING.md](CONTRIBUTING.md) if you intend
+to submit patches.
 
 I can often be found in the `#sway-devel` IRC channel with the
 nick `ifreund` on irc.freenode.net as well, or reached by email at