issues.dbk: rescue booting without root password

It may be too late to include this change in the bookworm release notes, however I thought that I'd try.

I believe that the issue note cherry-picked here and originally included for the bullseye release remains valid for bookworm. I have tested that the guidance included continues to work correctly on a bookworm system.

(I've also unarchived and re-opened #977358)

Closes: #977358 (cherry picked from commit ad648eb9)