bug#46702: Link symbol name in Help

[Eli Zaretskii <eliz@gnu.org>]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: Peter Dean <laszlomail@protonmail.com>,  46702@debbugs.gnu.org
> Date: Wed, 24 Feb 2021 17:59:17 +0100
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > I think we are splitting hair and painting the bike shed here.
> 
> Indeed, so I've just removed the "Documentation:" line.  This makes the
> output both more compact and less awkward to read, in my opinion.

I think this change may require rewording the beginning of the doc
strings.  E.g., look at this random sample:

  resize-mini-windows is a variable defined in ‘C source code’.

  Its value is ‘grow-only’

    You can customize this variable.
    This variable was introduced, or its default value was changed, in
    version 25.1 of Emacs.
    Probably introduced at or before Emacs version 21.1.

  How to resize mini-windows (the minibuffer and the echo area).
  A value of nil means don’t automatically resize mini-windows.
  A value of t means resize them to fit the text displayed in them.
  A value of ‘grow-only’, the default, means let mini-windows grow only;
  they return to their normal size when the minibuffer is closed, or the
  echo area becomes empty.

The "How to resize mini-windows..." part begins "out of the blue".
It's actually incorrect English (incomplete sentence), AFAIK.  It
reads okay-ish when the first line is alone, or when the text follows
some heading, like "Documentation:", but that is gone now.