add wireless instructions to documentation

[IngeGNUe]

I suggest to add another paragraph to section 7.1.3 like so:

To install the system, you would:

1. Configure the network, by running 'ifconfig eno1 up ... blablabla

For wireless, you would create a configuration file with the following
options:

network={
        ssid="foo"
        psk="bar"
}

And then run "wpa_supplicant -B -i wlp1s0 -c /path/to/config && dhclient
wlp1s0".