Readme updates corresponding to FireFly / Hyperledger project status

We need to do a substantial update to the README, as we move over to hyperledger.

We've been relying quite heavily on the docs on the Kaleido platform itself, and the README hasn't had enough love:
- Docs: https://docs.kaleido.io/kaleido-services/ethconnect/
- API docs: https://api.kaleido.io/ethconnect.html

Key items:
- [ ] Kaleido -> FireFly branding
- [ ] Merging in some of content from docs.kaleido.io into the FireFly docs section - @nickgaski might lean on you here
- [ ] Adding code contributor specific info, on the code layout - @nguyer has some content
- [ ] Pulling the Swagger in from api.kaleido.io - @peterbroadhurst can do this one