bug#29328: 24.5; doc string of `transpose-subr`

[Eli Zaretskii]

> From: Robert Pluim <rpluim@gmail.com>
> Cc: Drew Adams <drew.adams@oracle.com>,  29328@debbugs.gnu.org
> Date: Fri, 17 Nov 2017 15:25:43 +0100
> 
> >> See http://lists.gnu.org/archive/html/help-gnu-emacs/2017-11/msg00190.html
> >
> > I don't see how it can be meaningfully documented.
> 
> It's also only used by transpose-sexps. Perhaps rename the parameter
> to something like non-standard-calling-convention, even though that's
> far too long?

Not only is it too long, it is equally non-specific.