Add Mozilla Code of Conduct (#468)

* Add Mozilla Code of Conduct file

Fixes #467.

_(Message COC002)_

* remove extra from COC.md

CODE_OF_CONDUCT.md

@@ -0,0 +1,9 @@
+# Community Participation Guidelines
+
+This repository is governed by Mozilla's code of conduct and etiquette guidelines. 
+For more details, please read the
+[Mozilla Community Participation Guidelines](https://www.mozilla.org/about/governance/policies/participation/). 
+
+## How to Report
+For more information on how to report violations of the Community Participation Guidelines, please read our '[How to Report](https://www.mozilla.org/about/governance/policies/participation/reporting/)' page.
+