Document how to add the sleep state and minimal memory setup.
TEST=None
Change-Id: Ibebeef34269dbf2366f1bea6d734f6bade4e4028
Signed-off-by: Lee Leahy <leroy.p.leahy@intel.com>
Reviewed-on: https://review.coreboot.org/13446
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>