[M] Change in coreboot[main]: Documentation: Describe how SMMSTORE can be used safely

[Patrick Georgi (Code Review)]

Attention is currently required from: Benjamin Doron, Nico Huber.

Patrick Georgi has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/79095?usp=email )

Change subject: Documentation: Describe how SMMSTORE can be used safely
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Patch Set 2:

(1 comment)

File Documentation/drivers/smmstore.md:

https://review.coreboot.org/c/coreboot/+/79095/comment/82f8ba76_6f633268 :
PS2, Line 145:   - while doing so, process authentication data and reject invalid blocks;
> There's SMMSTOREv2 that changed a bunch of things, and it might come with two regions already. […]

Incomplete comment, so: Since I don't know exactly what the state of the art is, I'm merely collecting my thoughts here. I worked through the idea of having two regions as well, but deferred it for the first proof of concept.