[retro-gtk] (8 commits) 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:

  2192de2... WIP: Add, build, and deploy the reference manual

Commits added to the branch:

  651e17e... input: Make private structs as such for GTK-Doc
  af8633c... keyboard-key: Make private enums as such for GTK-Doc
  f3520e3... pixdata: Make private structs as such for GTK-Doc
  3d89c7e... pixdata: Fix the doc of retro_pixdata_new()
  dbcc30b... controller: Document RetroControllerInterface
  b55cd9b... version: Give the doc section a better name and title
  7f52c93... Allow building and installing the reference manual
  1126ae2... ci: Build and publish the reference manual