[retro-gtk] Non-fast-forward update to branch build-doc

[Adrien Plazas <aplazas src gnome org>]

The branch 'build-doc' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  1126ae2... ci: Build and publish the reference manual

Commits added to the branch:

  9c8fb8f... ci: Build and publish the reference manual