docs/mm: Physical Memory: add example of interleaving nodes

Add an example of memory layout with interleaving nodes where even memory
banks belong to node 0 and odd memory banks belong to node 1

Suggested-by: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20230213154447.1631847-1-rppt@kernel.org


Signed-off-by: Jonathan Corbet <corbet@lwn.net>