Removed unused link

PiperOrigin-RevId: 405624136

Author: andrewlewis

CONTRIBUTING.md

@@ -19,8 +19,6 @@ We will also consider high quality pull requests. These should normally merge
 into the `dev-v2` branch. Before a pull request can be accepted you must submit
 a Contributor License Agreement, as described below.
 
-[dev]: https://github.com/google/ExoPlayer/tree/dev
-
 ## Contributor license agreement ##
 
 Contributions to any Google project must be accompanied by a Contributor