bug#72521: [PATCH]: lisp/help-macro.el: remove hard-coded variable-pitch-mode

[Eli Zaretskii <eliz@gnu.org>]

> From: Paul W. Rankin <rnkn@rnkn.xyz>
> Date: Thu, 8 Aug 2024 19:37:56 +1000
> Cc: 72521@debbugs.gnu.org
> 
> > On 8 Aug 2024, at 18:58, Eli Zaretskii <eliz@gnu.org> wrote:
> > 
> > Thanks, but we cannot possible install this patch, since this behavior
> > was introduced in Emacs 29.  I agree with making this feature
> > optional, of course (and it will then be ON by default), but your
> > patch doesn't do that.
> 
> Hi Eli,
> 
> Thanks. I’ve replaced the call to variable-pitch-mode with a hook, 
> help-screen-hook, which defaults to calling variable-pitch-mode.
> 
> Ideally I think this should just be help-mode-hook though, which of 
> course should not default to calling variable-pitch-mode.
> 
> Anyway, how’s the patch (now attached) look to you?

Looks good, but I wonder whether a simple boolean user option would be
better, and also easier to customize.  After all this is not a mode,
so people will not expect it to have a hook.  Also, if someone doesn't
want variable-pitch-mode, I doubt they will want some other mode
instead, so the hook will most of the time be or the default or nil.

WDYT?