Namada specs pre-mainnet order of operations

[cwgoes]

• [ ] Clean up the current specs, aiming for a reasonable level of completeness and consistency with the codebase. Sub-tasks:
  • [ ] https://github.com/anoma/namada-docs/issues/277
  • [x] https://github.com/anoma/namada-docs/issues/201
  • [x] https://github.com/anoma/namada-docs/issues/200
  • [ ] https://github.com/anoma/namada-docs/issues/256
• [ ] Figure out specs versioning and the relation to codebase update processes
• [ ] Merge other existing documents such as the shielded sync & state sync HackMDs

Separately, we should think about what to do with the docs. I think those are easier to keep separately for now, so they can remain here, but we should still think about versioning and maintenance processes.