Remove duplicate release instructions (#273)

Author: benmccann

CONTRIBUTING.md

@@ -66,4 +66,4 @@ By contributing your code, you agree to license your contribution under the [MIT
 Releases
 -------
 
-To release, bump the version number in the `package.json` and `README.md`. Send a pull request, merge to `master`, and then `git pull` the merged PR. Switch to the release branch, `git rebase master`, and `git push`.
+See [the maintaining guide](Maintaining.md).