Document dosdevices/unc/

[Tobias Burnus]

Hello,

I found an email by Fergal Daly 
(http://www.mail-archive.com/wine-devel(a)winehq.org/msg08815.html) which 
kind of patches configuring.sgml to document dosdevices/unc.

I transformed it into a proper patch for configuring.sgml

Tobias