Tag the handbook the 22nd of each month

Our handbook has many changes each month. Historically, these used to be announced on the team call. These days however, hardly ever changes get announced, or you'd have to track certain channels where MRs get posted and track those.

This makes it really hard to keep up with the changes, and I know I start missing important changes, but there is no good way to keep up.

I'd propose to use git tags, and every 22nd of each month a new tag is created of the www-gitlab-com project. This way, the 23rd, I can ask for the diff between the current version, and last months change and be up to date.