Add "Code of Conduct" section

CONTRIBUTING.md

@@ -9,3 +9,7 @@ We love pull requests from everyone. The only stipulation is that you ensure the
 3. Push to your fork and [submit a pull request][pr].
 
 At this point you're waiting on us. We may suggest some changes or improvements or alternatives. The maintainers reserve the right to reject any resource that we feel does not add new information, or does not adhere to the [Open Code of Conduct](http://todogroup.org/opencodeofconduct/#awesome-community/[email protected])
+
+## Code of Conduct
+This project adheres to the [Open Code of Conduct][code-of-conduct]. By participating, you are expected to honor this code.
+[code-of-conduct]: http://todogroup.org/opencodeofconduct/#awesome-community/[email protected]