docs: remove markup
docs: remove markup

The overview chapters don't go through shorthand processing, so
don't use them there.

ahodesuka/gtk,chergert/gtk,Sidnioulz/SandboxGtk,davidgumberg/gtk,jadahl/gtk,grubersjoe/adwaita,Adamovskiy/gtk,Sidnioulz/SandboxGtk,chergert/gtk,chergert/gtk,ahodesuka/gtk,jigpu/gtk,Sidnioulz/SandboxGtk,ahodesuka/gtk,Lyude/gtk-,jigpu/gtk,alexlarsson/gtk,Lyude/gtk-,jigpu/gtk,Adamovskiy/gtk,davidgumberg/gtk,jadahl/gtk,alexlarsson/gtk,Sidnioulz/SandboxGtk,grubersjoe/adwaita,Lyude/gtk-,alexlarsson/gtk,grubersjoe/adwaita,jessevdk/gtk,jessevdk/gtk,jessevdk/gtk,Lyude/gtk-,Sidnioulz/SandboxGtk,davidgumberg/gtk,ahodesuka/gtk,jessevdk/gtk,Adamovskiy/gtk,jadahl/gtk,Adamovskiy/gtk,jigpu/gtk,jigpu/gtk,Lyude/gtk-,Adamovskiy/gtk,jigpu/gtk,davidgumberg/gtk,ahodesuka/gtk,alexlarsson/gtk,jessevdk/gtk,alexlarsson/gtk,Lyude/gtk-,Adamovskiy/gtk,jadahl/gtk,grubersjoe/adwaita,jessevdk/gtk,alexlarsson/gtk,ahodesuka/gtk,chergert/gtk,jadahl/gtk,davidgumberg/gtk,jigpu/gtk,jadahl/gtk,davidgumberg/gtk,chergert/gtk,grubersjoe/adwaita,grubersjoe/adwaita,jessevdk/gtk,jigpu/gtk,grubersjoe/adwaita,alexlarsson/gtk,Adamovskiy/gtk,jadahl/gtk,ahodesuka/gtk,grubersjoe/adwaita,Adamovskiy/gtk,chergert/gtk,Lyude/gtk-,davidgumberg/gtk,ahodesuka/gtk,chergert/gtk,chergert/gtk,Sidnioulz/SandboxGtk,Lyude/gtk-,jadahl/gtk,davidgumberg/gtk,alexlarsson/gtk