Add /fork shortlink

CONTRIBUTING.md

@@ -112,7 +112,7 @@ commits.
 Please follow this process; it's the best way to get your work included in the
 project:
 
-1. [Fork](http://help.github.com/fork-a-repo/) the project.
+1. [Fork](https://github.com/twbs/ratchet/fork) the project.
 
 2. Clone your fork (`git clone
    git@github.com:<your-username>/<repo-name>.git`).