Update _index.md

[ipaqmaster]

Fix wifi.recon.channel documentation. Preference gets reset when wifi.recon is toggled on though documentation doesn't reflect this. Might be better off as a set/get variable.

Further explanation

Bettercap ignores wifi.recon.channel if set before invoking wifi.recon on. wifi.recon.channel Must be called after wifi.recon on to have an impact.

For example - trying to avoid channels which the network interface describes as disabled under example command iw phy phy0 info |grep -E '[0-9]{4} MHz' with wifi.recon.channel x,y,z is entirely ignored when set before wifi.recon on gets issued.