bug#72961: Possible documentation improvement: Clarification for package installation

[Eli Zaretskii <eliz@gnu.org>]

> From: Krystian Samp <samp.krystian@gmail.com>
> Date: Thu, 5 Sep 2024 09:44:14 +0200
> Cc: philipk@posteo.net, 72961@debbugs.gnu.org
> 
> Thanks,
> 
> imho it'd be also useful to add there that Emacs will make the installed packages available automatically at
> startup. Now it reads that Emacs will add them to `load-path` but I wouldn't infer from this that Emacs will also
> make these packages available. And right after that we say that "... making the above manual customizations
> unnecessary for such packages" which specifically refers to loading, not only adding to `load-path`. Just two
> cents,

All of this is already described in the node "Package Installation",
to which this node points.  Cross-references in the manual are there
for a reason: interested readers are expected to follow them and to
read what the referenced nodes say.  We don't have the same
information in more than one place in the manual because that would
make it a maintenance burden: all of those places have to be found and
updated when something changes.  Our conventions are to describe each
feature in full in a single place, and then have cross-references to
that one place in other related places.

So I decided not to expand on this more in the sections which is only
tangentially related to package installation.  This text is there so
as to avoid creating an impression that what this node describes must
be done for packages installed via package.el.  It doesn't (and should
not) pretend to describe installation via package.el.