Readme references Fedora 29, that should be updated and more dists added.

[lukehinds]

As per subject, validate against Fedora 31 and state which RHEL / CentOS versions are supported.

[dawud]

Work in progress in #17. I have added support for Fedora 31 and some other bits.
Adding Fedora 30 would be easy. I'd suggest to drop support for Fedora 29 and previous releases since those are EOL-ed.