Add commit message link to newbie message

Change-Id: I271fa24a73baf16da97f42c86cd1563c9ad0df4a
diff --git a/jeepyb/cmd/welcome_message.py b/jeepyb/cmd/welcome_message.py
index ebc026e..ae473cc 100644
--- a/jeepyb/cmd/welcome_message.py
+++ b/jeepyb/cmd/welcome_message.py
@@ -90,6 +90,7 @@
 
     IRC: https://wiki.openstack.org/wiki/IRC
     Workflow: https://wiki.openstack.org/wiki/Gerrit_Workflow
+    Commit Messages: https://wiki.openstack.org/wiki/GitCommitMessages
     """
     # post the above message, using ssh.
     command = ('gerrit review '