[Documentation] How to install

[Bellavene]

Now readme states Usage: prefs-export [OPTIONS], but there is no executable to deal with in the first place.
I believe, there is a need for better installation instructions.

[Tatsh]

The package is on PyPI. The easiest way to install is to use Pip: pip install --user macprefs (you then need to have the path it uses (e.g. ~/.local/bin) in PATH). Also I made sure the latest version is published there.

If you use MacPorts there is a port in my source but it is outdated and I do not use macOS very much anymore to make it worth it to maintain this source.