doc/flatpak-metadata: Fix a couple typos
doc/flatpak-metadata: Fix a couple typos

Closes: #3096
Approved by: alexlarsson

flatpak/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,matthiasclasen/flatpak