please add AppStream appdata.xml file

[sergiomb]

Hi,
AppStream - Infrastructure for distro-agnostic software-centers and universal software component metadata
is wildly use on Linux distros , we need it on Fedora and I did one [1] , but you can distribute it
Thank you.


[1]
https://pkgs.rpmfusion.org/cgit/free/sm ... 862c85e981

References:
https://docs.fedoraproject.org/en-US/pa ... s/AppData/
https://www.freedesktop.org/software/ap ... esktopApps
https://www.freedesktop.org/software/appstream/docs/