Bug#538265: Add disable netcfg preseed option

[Frans Pop <elendil@planet.nl>]

On Friday 24 July 2009, Anthony L. Awtrey wrote:
>  > Please also provide a patch for the installation guide to document
>  > the new option.
>
> I've downloaded the installation-guide package and looked for other,
> similar configuration settings. It seemed like the most obvious spot
> was in the debconf variable example here:
>
> http://d-i.alioth.debian.org/manual/en.i386/apbs04.html

Correct, that is the most essential place.
It could potentially also be listed in the section listing boot parameters 
(5.3.1), but that is debatable.

> The attached diff puts the netcfg/enable option at the top of the list
> with an explanation and left it commented out.

Patch looks fine and can be committed when the change in netcfg is 
committed.

Thanks,
FJP