bug#10541: 24.0.92; doc string of `customize-unsaved'

[Drew Adams]

> > 2. This is not so much in order to customize as it is to 
> >    check changes that have been made during the session.
> >    The current doc string misses the main purpose.
> 
> "Customize" in this context means "edit using the Customize 
> interface".  No need to clutter up the docstring.

It sounds like you missed the point.  Users use this function not so much to
"edit using the Customize interface" as to check unsaved changes to see if they
might want to save some.  99.999% of the time I expect users will do no editing.
They will simply save or not (exit without saving).

This function is _not_ about _editing_ or _customizing_.  It is about using "the
Customize interface" to _check_ unsaved values.