Doc/mb/lenovo/Sandy_Bridge_series.md: Clarify installation

Unlike Ivy Bridge series, there isn't a method to flash coreboot
internally when running vendor firmware (yet). Until someone finds a way
to bypass flash protections, the first flash has to be done externally.

Change-Id: Idaff264f2b7277516d69d1323f1a0c885b28c3db
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/49848
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>

0 files changed, 0 insertions, 0 deletions