bug#17567: 24.4.50; doc string of `define-derived-mode'

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Sat, 25 Sep 2021 12:07:02 -0700
> Cc: drew.adams@oracle.com, 17567@debbugs.gnu.org
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > The first is a variable, the second is a symbol.  "Unquoted symbol" is
> > something that causes at least me to raise a brow.
> 
> Is it better to delete that sentence and leave it as it was, or is there
> something else we could usefully put as an explanation?

I think it's better to delete it.

In general, when the symbol's value is needed, we don't say anything.
When the symbol itself is needed, we sometimes say it should be a
symbol, as in the case of add-hook:

  HOOK should be a symbol, ...

So I think in this case we don't need to say anything.