Add email address to CoC (#923)

* Add email address

* Update CODE_OF_CONDUCT.md

Author: rcannood

CODE_OF_CONDUCT.md

@@ -61,7 +61,7 @@ representative at an online or offline event.
 
 Instances of abusive, harassing, or otherwise unacceptable behavior may be
 reported to the community leaders responsible for enforcement at
-[INSERT CONTACT METHOD].
+[community@openproblems.bio](mailto:community@openproblems.bio).
 All complaints will be reviewed and investigated promptly and fairly.
 
 All community leaders are obligated to respect the privacy and security of the