Change in coreboot[master]: Documentation: Improve x86_64

[Patrick Rudolph (Code Review)]

Attention is currently required from: Patrick Rudolph, Arthur Heymans.
Patrick Rudolph has uploaded a new patch set (#4) to the change originally created by Patrick Rudolph. ( https://review.coreboot.org/c/coreboot/+/56017 )

Change subject: Documentation: Improve x86_64
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Documentation: Improve x86_64

* Move to own markdown document
* Better describe current implementation
* Update TODOs

Change-Id: Ia5ba51be629a8c878aad64d3297176457cf8e855
Signed-off-by: Patrick Rudolph 
---
M Documentation/arch/x86/index.md
A Documentation/arch/x86/x86_64.md
2 files changed, 141 insertions(+), 92 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/17/56017/4