Cashtab README is out of date and unhelpful for newA few related improvements to make Cashtab more accessible for devs.
The complicated step of building all local deps should be scripted and documented.
Do this,1. We script the complicated prep and installation of local dependencies
2. We update the README to reference the script (and remove obsolete stuff)
3. remove obsolete docsWe add a `.env.example` file to show what env vars are used by Cashtab.