Documentation about Praos and the HFC/civic time

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I've long wanted to write down the Cardano-specific instantiation of the Praos protocol theorem.

This is that document, plus some discussions related to work currently in the IOE innovation pipelines as well as some trade-offs I've been struggling to judge regarding the HFC's behaviors in disaster scenarios. The second document elaborates on the HFC concerns.

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Rendered: https://github.com/IntersectMBO/ouroboros-consensus/blob/nfrisby/docs-CardanoPraos/docs/website/contents/for-developers/CardanoPraosBasics.md

Rendered: https://github.com/IntersectMBO/ouroboros-consensus/blob/nfrisby/docs-CardanoPraos/docs/website/contents/for-developers/CivicTime.md