[RFC, doc] Fix -stack-list-arguments parameter description

[Eli Zaretskii]

> From: Vladimir Prus <vladimir@codesourcery.com>
> Date: Fri, 30 Oct 2009 20:38:28 +0300
> 
> Current docs for -stack-list-arguments fails to document the '2'
> value of the 'show-values' parameter. This patch fixes that, while
> making the naming of parameter consistent with -stack-list-locals
> and -stack-list-variables. OK?

Yes, thanks.  One small request, though:

> +If @var{print-values} is 0 or @code{--no-values}, print only the names of
> +the variables; if it is 1 or @code{--all-values}, print also their
> +values; and if it is 2 or @code{--simple-values}, print the name,
> +type and value for simple data types and the name and type for arrays,
> +structures and unions.              ^

Please add a comma where shown.