Update chores process for new metadata field
Because the script that processes pages that aren't in the navigation is changing: gitlab-docs!4846 (merged), we also need to change the process.
Because we don't have a huge number of pages that aren't in the navigation and aren't excluded anymore, we probably don't need to ask for issues etc. We can go straight to MRs.
Helps solve: gitlab-docs#1794 (closed).
CC @sarahgerman
Edited by Evan Read