Merge branch 'patch-58' into 'master'

Fix typo in  "Milestones documentation"

See merge request gitlab-org/gitlab!23996

doc/user/project/milestones/index.md

@@ -64,7 +64,7 @@ You can delete a milestone by clicking the **Delete** button.
 
 ### Promoting project milestones to group milestones
 
-If you are expanding from a few projects to a larger number of projects within the same group, you may want to share the same milestone among multiple projects in the same group. If you previously created a project milestone and now want to make it available for other milestones, you can promote it to a group milestone.
+If you are expanding from a few projects to a larger number of projects within the same group, you may want to share the same milestone among multiple projects in the same group. If you previously created a project milestone and now want to make it available for other projects within the same group, you can promote it to a group milestone.
 
 From the project milestone list page, you can promote a project milestone to a group milestone. This will merge all project milestones across all projects in this group with the same name into a single group milestones. All issues and merge requests that previously were assigned one of these project milestones will now be assigned the new group milestones. This action cannot be reversed and the changes are permanent.