Re: doc elisp intro cross reference fixes

[Stefan Monnier]

> I don't know what the idea was behind trying to "guess" a
> customization group, so I won't comment on that.

The idea is that most elisp packages declare one group at the beginning
and then put all their defcustom in that group, so I wanted to remove this
redundancy by allowing people to skip the :group and know that the most
recently declared group would be used.


        Stefan