Add contributor/development instructions?

It was a pretty wild ride to get my local copy properly linked with my local dev app.

I had to yarn link:

- `graphql-compose`
- `graphql-compose-mongoose`
- `graphql-compose-pagination`
- `graphql-compose-connection`
- `graphql` (from `graph-compose`)
- `mongoose`

Not sure if this is typical workflow.

Could we maybe provide add instructions (here or to `graphql-compose`, or the `graphql-compose-examples`) for getting up and running with an app using local copies.

That said, it was super easy to run tests 👍

Working on some new features. I have recursive operators in the works, some tests written, few more to write, implementation works with my local app.

Sneak peek: