Bring architecture docs into the community

[peterbroadhurst]

The full code history is in this repo, including Generation 1.
However, the architecture design of Generation 2, and collaboration history on things like PRs etc. isn't.

So I'm making this task (while we are in the pre-foundation process evaluation phase with Hyperledger) to take architecture diagrams and notes and put them into issues..

Particular on areas where in Generation 2 there is active code development happening, that is evolving quickly.