Update documentation for sidebar metadata

Items moved from sidebar to ellipsis dropdown:

Merge requests !87727 (merged)

• Notifications
• Lock merge request
• Copy reference

Docs- https://docs.gitlab.com/ee/user/project/merge_requests/#move-sidebar-actions

Issue

• Notifications
• Lock issue
• Copy reference (can't find in current documentation)
• Copy email

Current docs- https://docs.gitlab.com/ee/user/profile/notifications.html#edit-notification-settings-for-issues-merge-requests-and-epics

If you don’t see this action on the right sidebar, your project or instance may have enabled a feature flag for moved sidebar actions.

Epics

• Notifications
• Copy reference (can't find in current documentation)

Incidents

• Notifications
• Copy reference (can't find in current documentation)
• Copy email

Alerts No changes