Add Installation section to readme

[ReillyBrogan]

If a distribution package is available then that should be preferred over building manually.

This change is inspired by a few recent issues which were seemingly caused by missed steps during building.

[PixlOne]

Slight nitpick, logiops-git is not on the official arch repos and you would need some AUR helper, so pacman -S logiops-git isn't really valid.