Added opensource@dealerdirect.nl email to the documentation.

Author: frenck

CONTRIBUTING.md

@@ -80,7 +80,7 @@ further defined and clarified by project maintainers.
 ### Enforcement
 
 Instances of abusive, harassing, or otherwise unacceptable behavior may be
-reported by contacting the project team at [INSERT EMAIL ADDRESS]. All
+reported by contacting the project team at opensource@dealerdirect.nl. All
 complaints will be reviewed and investigated and will result in a response that
 is deemed necessary and appropriate to the circumstances. The project team is
 obligated to maintain confidentiality with regard to the reporter of an incident.