[L] Change in coreboot[main]: Documentation: Add Timestamp documentation

[Martin L Roth (Code Review)]

Attention is currently required from: Nicholas Chin.

Martin L Roth has posted comments on this change by Martin L Roth. ( https://review.coreboot.org/c/coreboot/+/87186?usp=email )

Change subject: Documentation: Add Timestamp documentation
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Patch Set 3:

(1 comment)

Patchset:

PS3: 
Hrm - it looks like we already had timestamp documentation in the lib directory. I'm not sure how I missed that.

I'll combine this document with what already exists