bug#4422: diff-switches is a bad idea

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: rrt@sc3d.org,  4422@debbugs.gnu.org
> Date: Wed, 02 Oct 2019 13:47:12 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > I think the current situation is reasonable, since to resolve it the
> > user could customize vc-diff-switches or vc-cvs-diff-switches to t to
> > avoid this problem.
> 
> Perhaps we should mention this in the diff-switches doc string?  That'd
> make it more obvious for the user how to resolve the problem.

Fine with me, thanks.