[coreboot] Some updated instructions to flash coreboot to the Thinkpad X60 from vendor bios

[Arthur Heymans]

Hi

With some new code and methods the process of flashing a thinkpad x60
from vendor bios (and to some extend a thinkpad t60) can be eased a bit
and wrote down a hopefully useful guide:

Here is the link:
https://gist.github.com/ArthurHeymans/c5ef494ada01af372735f237f6c6adbe

Feedback is of course very welcome.
(I'll try to put on the wiki some time later)

Kind regards

Arthur