Add metadata to MR versions doc page

Add Code Review metadata to MR versions doc page

doc/user/project/merge_requests/versions.md

 ---
-stage: none
-group: unassigned
+stage: Create
+group: Code Review
 info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
 type: reference, concepts
 ---