Add details of maintainer mentorship
Do after #3266 (closed)
At this point, we might want to move https://about.gitlab.com/handbook/engineering/#how-to-become-a-maintainer to its own page, and link to that from https://about.gitlab.com/handbook/engineering/projects/.
Aside from that, we need to say:
- How the mentorship works (you get direct, regular feedback from a buddy maintainer).
- If the buddy is fixed, or you cycle through the existing maintainers.
- @gitlab-org/maintainers/rails-backend wdyt the best option is?
- How to update reviewer roulette to put yourself in the rotation (dennis/reviewer-roulette#8 (closed)).
- How this works on the team page.