fix link

Author: Devlin Junker

CONTRIBUTING.md

@@ -94,4 +94,4 @@ If you make changes in `@uirouter/core`, run these scripts before rebuilding or
 - `npm run watch`: Continuously builds the `@uirouter/core` code when sources change.
 
 ## Updating Angular Versions
-See [notes in add_support_for_new_angular_version.txt](./add_support_for_new_angular_version.txt) for steps to update the angular dependency version
+See notes in [add_support_for_new_angular_version.txt](./add_support_for_new_angular_version.txt) for steps to update the angular dependency version