Adds prereq for pipeline schedules
What does this MR do and why?
When a project is archived, any active pipeline schedules continue to run even though the project is read-only. In this case, users should either deactivate or delete any active pipeline schedules before a project is archived.
This MR updates the description to clarify this behavior and adds a prerequisite to the Archive a project section.
Slack thread: https://gitlab.slack.com/archives/CPCJ8CCCX/p1708560514829799
Review app: https://main-ee-145608.docs.gitlab-review.app/ee/user/project/working_with_projects.html#archive-a-project
Edited by Lysanne Pinto