Improve documentation

[frankharkins]

What is the expected enhancement?

• Project overview doc
• How to make a project compatible with ecosystem
  • configure tests
  • ecosystem.json
  • make it clear what commands the ecosystem tests actually run
• finalise ecosystem rfc

[mickahell]

For the how to make project compatible :
If it can help, I created this project as a very simple template project for ecosystem member :

• https://github.com/mickahell/qiskit-ecosystem_template

Also this project should also do the job as a perfect very complete project (I didn't test if it pass the whole set of checks yet) :

• https://github.com/qiskit-community/quantum-prototype-template

[frankharkins]

Thanks! The prototype repo doesn't pass as it doesn't have a qiskit requirement (#494)

[mickahell]

Thanks! The prototype repo doesn't pass as it doesn't have a qiskit requirement (#494)

Hmm weard, I'll check it and make it pass.

[mickahell]

FYI : qiskit-community/quantum-prototype-template#73