Updates patch release documentation
What does this MR do?
Updates patch release documentation associated with the maintenance policy extension (gitlab-com/gl-infra&828 (closed)).
- Re-arranges the patch release pressure document and adds a section about determining if there are unreleased merge requests on the active versions.
- Updates the stable branch documentation to account for the new process.
Related to gitlab-com/gl-infra/delivery#2839 (closed)
Edited by Mayra Cabrera