Add missing Issue pages to global nav
Related: gitlab#218665 (closed)
These pages haven't been listed in the global nav:
- https://docs.gitlab.com/ee/user/project/issues/associate_zoom_meeting.html
- https://docs.gitlab.com/ee/user/project/issues/crosslinking_issues.html
- https://docs.gitlab.com/ee/user/project/issues/issue_data_and_actions.html
- https://docs.gitlab.com/ee/user/project/issues/managing_issues.html
- https://docs.gitlab.com/ee/user/project/issues/multiple_assignees_for_issues.html
- https://docs.gitlab.com/ee/user/project/issues/sorting_issue_lists.html