I'm totally agree.with you @lvicentini
The actual doc, the Administrator Manual http://docs.nethserver.org/en/latest/ is GOOD, really.
But we need other type of doc, for other kind of public.
It's not the first reflex to go to the Administrator Manual for a quick search.
We have a wiki, for this, and feel free to help us to fill it 
The wiki is not old, and we really need help