bug#6344: 24.0.50; doc of menu separators

[Drew Adams]

> > I just spent some time myself rediscovering this.
> > Can we please fix the doc to mention this?  Thx.
> >
> >> A user will naturally wonder, "Is there no way to specify 
> >> :enable or :visible for a menu separator?"  In fact, there
> >> is a way, simply use:
> >>  (menu-item SEPARATOR-TYPE nil :visible PREDICATE)
> >> etc.
> >>  
> >> In sum, the doc (spec) for separators is incomplete.
> 
> Could you suggest an appropriate text for the manual?

I think all we need to say is something like this (in node `Menu Separators'):



You can use this longer form to specify keywords such as :enable and :visible
for a menu separator:

  (menu-item SEPARATOR-TYPE nil . ITEM-PROPERTY-LIST)

For example:

  (menu-item "--" nil :visible (boundp 'foo))