bug#15506: 24.3; checkdoc docstrings "non-nil"

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Wed, 24 Feb 2016 15:05:11 +1100
> Cc: 15506@debbugs.gnu.org
> 
> Kevin Ryde <user42@zip.com.au> writes:
> 
> > This is an idea to have checkdoc propose "non-nil" at the start of
> > docstrings, rather than "true".
> >
> > For variables this is per the last tip in "(elisp)Documentation Tips".
> > The functions bit extends on similar lines.
> >
> > Maybe the function form could report further variations, eg. `eventp'
> > starts "True if the argument ...".
> 
> I think this makes sense.  Any objections to applying?

None here.