bug#3615: 23.0.94; (elisp)Local Variables: xrefs to nodes for buffer-local and frame-local vars

It would help to add a cross reference in this Info node to the nodes
that explain buffer-local vars and frame-local vars, saying that this
is a different notion of "local" variable.
 
And vice versa. Put xrefs at the nodes about buffer-local and
frame-local, pointing to the other nodes (e.g. Local Variables).
 
The aims are to (1) point to the other nodes, and (2) say that these
are not closely related, in spite of their similar names.
 
This would help because users are not necessarily clear that these are
different critters, and looking for info about one, they might end up
mistakenly reading about another, perhaps without even realizing it.

In GNU Emacs 23.0.94.1 (i386-mingw-nt5.1.2600)
 of 2009-05-24 on SOFT-MJASON
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4)'