docs: fix link

Author: andreastt

CONTRIBUTING.md

@@ -249,6 +249,6 @@ Issues are labelled to make them easier to categorise and find by
 
 ## Communication
 
-Selenium contributors frequent the [`#selenium` channel on
+Selenium contributors frequent the `#selenium` channel on
 `[irc.freenode.org](https://webchat.freenode.net/)`. You can also join
 the `selenium-developers@` mailing list](https://groups.google.com/forum/#!forum/selenium-developers).