bug#21728: 25.0.50; [patch] mention focus-{in,out}-hook in manual

[Eli Zaretskii]

> Date: Tue, 23 Feb 2016 17:59:21 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: aaronecay@gmail.com, 21728@debbugs.gnu.org
> 
> > From: Lars Ingebrigtsen <larsi@gnus.org>
> > Cc: Aaron Ecay <aaronecay@gmail.com>,  21728-done@debbugs.gnu.org
> > Date: Tue, 23 Feb 2016 16:31:47 +1100
> > 
> > Eli Zaretskii <eliz@gnu.org> writes:
> > 
> > > No, they are also mentioned in the node "Input Focus".  And the node
> > > "Focus Events", where you suggested the addition, has a
> > > cross-reference to "Input Focus", near its beginning.  So perhaps what
> > > we need is a sentence near that cross-reference that somehow mentions
> > > these two hooks, and all the rest is already in place?  Would you like
> > > to suggest an alternative patch along these lines?
> > 
> > Hm...  is that really necessary, though?  With that xref it seems pretty
> > clear that the user should go to that node for more info on everything
> > connected with input focus, I think...
> 
> The xref doesn't mention the hooks.  I suggested to add a single
> sentence that does, that's all.

Now done on the emacs-25 branch.