bug#22598: 'info guix' fails on guixSD

[myglc2 <myglc2@gmail.com>]

'man guix' is quite likely the first thing a new user types. The man
page is a stub to 'info guix'...

GUIX(1)
[...]
       If the info and guix programs are properly installed  at  your
       site, the command

              info guix

       should give you access to the complete manual.

However, on guixSD, 'info guix' produces 'bash: info: command not
found'.

While this result is technically understandable, it does seem rather
user-unfriendly.

Work arounds (tested on guixSD) are ...

1    guix environment guix
     info guix

2    tell the user that if info doesn't work, install it.

But both of these seem like bad things to say on the first man page.

From a usability point of view, it would probably be best to include
info in the global guixSD packages.

SIDE THOUGHT:

I love reading and using info in emacs. However, I will do almost
anything to avoid having to use the actual info program. I expect many
potential guix users are the same, or, more likely, have never heard of
info.

To improve the "man-points-to-info" man strategy (which I fully support)
perhaps guixSD and guix should include a user-friendly info reader and
the man page should point to that.