bug#59609: 29.0.50; [PATCH] Better advertise (Non-)GNU ELPA in emacs manual

[Eli Zaretskii]

> Cc: Stefan Monnier <monnier@iro.umontreal.ca>
> From: Stefan Kangas <stefankangas@gmail.com>
> Date: Sat, 26 Nov 2022 05:44:17 -0800
> 
> --- a/doc/emacs/package.texi
> +++ b/doc/emacs/package.texi
> @@ -35,8 +35,10 @@ Packages
>  name of a package, and displays a help buffer describing the
>  attributes of the package and the features that it implements.
>  
> -  By default, Emacs downloads packages from a package archive
> -maintained by the Emacs developers and hosted by the GNU project.
> +  By default, Emacs downloads packages from GNU ELPA
> +(@url{https://elpa.gnu.org/}), a package archive maintained by the
> +Emacs developers and hosted by the GNU project.  It also downloads
> +packages from NonGNU ELPA (@url{https://elpa.nongnu.org/}).

This sounds OK, but begs the question: what's short description of NonGNU
ELPA?  Since we describe GNU ELPA, let's also describe the other one.  The
purpose should IMO be to explain to the reader, or at least hint why we
maintain two separate archives.

Thanks.