docs: updating changes requests to include assigning groups

We don't mention that you can assign members of groups as reviewers. Adding this in.

Author: Robert Norrie

docs/docs/advanced-use/change-requests.md

@@ -34,7 +34,7 @@ You will need to provide:
 
 - The title of the Change Request
 - Optionally a description of the reason for the Change Request
-- Any number of assignees. These people will receive an email alerting them of the Change Request
+- Assigness - specify either individual users or members of a group. These users will receive an email alerting them of the Change Request
 
 ## Approving a Change Request