From: Justin Forbes on
gitlab.com
https://gitlab.com/cki-project/kernel-ark/-/merge_requests/1063#note_5725...
The scripts that generate these requests also go through RHMAINTAINERS
and look for the proper reviewer. They are added via the Cc Lines in
the MR, and that is how they are added as reviewers even if not a
member of the project. I am not sure why it doesn't allow you to add
non members via the UI but it does work via Cc lines.