Add OARS tags to the appdata
Summary: OARS tags allow software centers such as Discover, GNOME Software or the Flathub website to generate content ratings for age etc.. This is pretty useful for an app like gcompris as it can advertise how appropriate it us for users of all ages.
Reviewers: GCompris, jjazeix
Reviewed By: GCompris, jjazeix
Subscribers: jjazeix, KDE Edu
Differential Revision: https://phabricator.kde.org/D12688