Some general Consensus Layer architectural documentation

[nfrisby]

While designing/criticizing other high-level components, I think we've identified some pillars of the design.

I think a narrowly scoped document focusing on those pillars could be useful for multiple audiences. EG it could be a quick reference for the architects when trying to relate new ideas to the already-identified key concepts. EG it could help new contributors chart a path for understanding the architecture, etc.

In the Diátaxis framework, I would imagine this is at least in the "Reference" category. Specifically "quick reference for use by experts".

[nfrisby]

Some ideas from my notes:

• A lexicon.
• The general categories of ways a header and/or block and/or tx can be invalid (notably in-future check).
• Why k blocks and 3k/f slots are so relevant (see HardWonWisdom.md).
• What "caught-up" fundamentally means.
• Mempool and block forge as a "client".
• Where time translations are used.
• Etc.