Merge branch 'jramsay-maintainers-can-edit-docs' into 'master'

Update merge request maintainer access docs

See merge request gitlab-org/gitlab-ce!17864

doc/user/project/merge_requests/maintainer_access.md

 # Allow maintainer pushes for merge requests across forks
 
+> [Introduced][ce-17395] in GitLab 10.6.
+
 This feature is available for merge requests across forked projects that are
-publicly accessible. It makes it easier for maintainers of projects to collaborate
-on merge requests across forks.
+publicly accessible. It makes it easier for maintainers of projects to
+collaborate on merge requests across forks.
 
-When enabling this feature for a merge request, you give can give members with push access to the target project rights to edit files on the source branch of the merge request.
+When enabled for a merge request, members with merge access to the target
+branch of the project will be granted write permissions to the source branch
+of the merge request.
 
-The feature can only be enabled by users who already have push access to the source project. And only lasts while the merge request is open.
+The feature can only be enabled by users who already have push access to the
+source project, and only lasts while the merge request is open.
 
 Enable this functionality while creating a merge request: