bug#19628: 25.0.50; doc of button functions

[Eli Zaretskii]

> Date: Tue, 20 Jan 2015 10:51:20 -0800 (PST)
> From: Drew Adams <drew.adams@oracle.com>
> Cc: 19628@debbugs.gnu.org
> 
> As I said, in `Manipulating Buttons', for example, the description of
> `button-activate' refers to "BUTTON's `action' property".  That property
> is not explained there, so there should be a cross-ref from there to the
> place where it is described: `Button Properties'.

OK, I added a few words about 'action' there.  (Having a
cross-reference just to save a sentence or two didn't sound right.)