sg: allow running enterprise env with `sg`, flesh out TODO/Inspiration/Quickstart/Hacking in README
Created by: mrnugget
This updates the sg.config.yaml
so that sg run-set enterprise
boots up the enterprise environment (still without the @sourcegraph/code-intel commands though, wink wink, nudge nudge).
It also updates the README to contain more TODOs, an Inspiration section, an updated Quickstart/Installation section and a Hacking section.