Doc enhancement

[Bzzzz]

Hi maillisters,


my concern is about the site's doc.

I spent a lot of time before getting the configuration files right
because of a small lack in the doc:

it is missing a few lines explaining that what's appears a "weird"
network notation has in fact 2 purposes, setting the VPN interface IP
address and the segment width.

This simple supplementary explanation could spare a lot of potential
users hours of ranting… ;)

Disclaimer: I don't do very much networking apart the usual into
Linux, so not on the head (nor the balls!)

Jean-Yves