Bug#680377: xorg: update FAQ: How to set correct DPI

[Carsten Otto <otto@informatik.rwth-aachen.de>]

Package: xorg
Version: 1:7.6+13
Severity: normal

Dear Maintainer,

the FAQ at http://x.debian.net/faq/general.html currently mentions three
ways how to set DPI values different from 96 DPI:

 - use the desktop environment
 - use -dpi argument for X
 - use xrandr --dpi

Please also add the possibility to use the "DisplaySize" option in the X
config (especially because none of the three ways listed above work for
me).

Julien Cristau also mentioned setting something for xft, but I have no
further insights. However, this also may be useful for the FAQ.

PS: While you're at it, it would be very nice to see how to supply -dpi
as an argument when using gdm3 (or any other login manager).

Best regards,
Carsten Otto