Added Experimenter link to readme

README.md

@@ -33,4 +33,5 @@ See [DEV.md](./docs/DEV.md) for more details on how to work with this add-on as
 
 ## References
 
+* [Experimenter](https://experimenter.services.mozilla.com/experiments/TODO/)
 * [Bugzilla](https://bugzilla.mozilla.org/show_bug.cgi?id=TODO)