bug#46236: 26.1; explicit the info files installation

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Tue, 20 Apr 2021 22:20:03 -0500
> Cc: marmot-te <marmot-te@riseup.net>, 46236@debbugs.gnu.org
> 
> Richard Stallman <rms@gnu.org> writes:
> 
> >   > I suggest to add a notice in the info/dir file itself (or at least
> >   > an info link easy to notice, be it to the FAQ or not) that
> >   > explicit that you probably need to install system-wise :
> >   > - extra documentations packages such as bash-doc,
> >   >   emacs-common-non-dfsg (non-free repository for debian).
> >   > - ensure texinfo is installed in order to compile documentation
> >   >   when new emacs packages are installed.
> >
> > In principle this is desirable, but it may be complex.  For instance,
> > on various GNU/Linux distros the method is different.
> 
> Let's assume for the sake of argument that we only want to do this for
> Debian and derivatives.  That would require adding the non-free
> repository, thus indirectly encouraging users to use proprietary
> software.  Is that something we really would want to do?

That depend on what we say.  We don't have to mention Debian or their
repository explicitly -- which would also be better because other
distros could have a similar problem.

My problem with the suggestion is that I don't have a good idea where
to add the message.  We could:

  . display a special message when a manual is supposed to be part of
    Emacs; or
  . modify the message in case of a manual that wasn't found to better
    indicate that the user should try installing it

We could also do both.

But I don't think we should name the specific distros or their
specific package names; that way lies madness of having to maintain
those names forever.