WIP: Adds Instructions for Installing on FreeBSD

[tuaris]

This adds installation instructions for FreeBSD using the port or package. I'm not familiar with Hugo so I apologize if something is incorrect.

NOTE: Don't merge until the port has been added to FreeBSD. I will remove the "WIP" prefix once that's done.

[deluan]

Hey @tuaris, has the port been added to FreeBSD already? Can we merge this?

[tuaris]

@deluan this can be merged, Navidrome has been added to the official FreeBSD ports tree: https://www.freshports.org/multimedia/navidrome/