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

[Frédéric Delanoy]

On Tue, Jul 23, 2013 at 5:26 PM, Frédéric Delanoy
<frederic.delanoy at gmail.com> wrote:
> ---
>  Make.rules.in | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/Make.rules.in b/Make.rules.in
> index fda8e81..d326247 100644
> --- a/Make.rules.in
> +++ b/Make.rules.in
> @@ -100,7 +100,7 @@ dummy:
>
>  # Manual Dependencies
>
> -ALLFORMATS = html pdf sgml ps txt
> +ALLFORMATS = html pdf ps txt

Please discard this patch ; it seems to be used in the translated
guides to generate sgml from english version+po file