Please add build instructions for FreeBSD

[tuaris]

Is your feature request related to a problem? Please describe.
Build instructions currently do not show steps for FreeBSD

Describe the solution you'd like
Functional build instructions for FreeBSD

Describe alternatives you've considered
N/a

Additional context
FreeBSD is a very popular, API/ABI stable OS that is the original UNIX. It's much easier to target for development due to it's stable development, and simpler to use due to it being packaged together as a whole OS like MacOS and Windows. Having Kaspa provide official support for FreeBSD ensures you do not exclude a whole segment of users.