manjaro: Switch from versioning to rolling

This is something that can only be done as we never ever included Manjaro 19 as part of a release.

After some talks with Manjaro community, they expressed that having the distro represented as a rolling is better for them as it'd lower the maintainance needed and also let the users have the most up-to-date content when using osinfo-db links (which will be added soon) to download it.

Signed-off-by: Fabiano Fidêncio fidencio@redhat.com