[libadwaita] (5 commits) Non-fast-forward update to branch wip/exalm/migration-guide

[Adrien Plazas <aplazas src gnome org>]

The branch 'wip/exalm/migration-guide' 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:

  38e982d... doc: Add a migration guide from libhandy 1.4

Commits added to the branch:

  04a4d46... docs: Fix headers for build docs and visual index (*)
  ef41cc7... docs: Don't mention autotools (*)
  ce5f4b5... docs: Fix the flatpak manifest example (*)
  16e48fc... docs: Fix the macOS build instructions (*)
  c370cac... doc: Add a migration guide from libhandy 1.4

(*) This commit already existed in another branch; no separate mail sent