[docs] "sgml" is not a valid output format

[Francois Gouget]

On Tue, 23 Jul 2013, Frédéric Delanoy wrote:
[...]
> -ALLFORMATS = html pdf sgml ps txt
> +ALLFORMATS = html pdf ps txt

'make sgml' can be used to generate the translated SGML source files for 
our many documentation translations. So I don't think this patch should 
be applied.

-- 
Francois Gouget <fgouget at free.fr>              http://fgouget.free.fr/
          The last time religion ruled, it was called the dark ages.