Add repology badge showing packaging status

[ehaupt]

I've created a FreeBSD port for UxPlay.

This pull request adds:

• a repology badge showing the packaging status across *BSD's/Linux Distros.
• instructions on how to install a package on FreeBSD
• instructions on how to install a package on Debian based systems

[fduncanh]

This is just to add info to README?

[fduncanh]

@ehaupt thanks for your great work on this.

I put your nice repology badge into a reworked README