Document the steps necessary to enable serial output
TEST=None
Change-Id: Ifc0e700d7ef54fb1e28ca9bca34b94cccd3633ac
Signed-off-by: Lee Leahy <leroy.p.leahy@intel.com>
Reviewed-on: https://review.coreboot.org/13444
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
66decf1644
