message: Update README w/ codegen instructions
diff: @@ -84,3 +84,19 @@ To impersonate the account get a new Client and pass in the account id.
  let customers = stripe::Customer::list(&client, params).unwrap();
  println!("{:?}", customers); // => List { data: [Customer { .. }] }
  ```
  +
  +## Contributing
  +
  +### Code Generation
  +This library is (mostly) authored via code generation by parsing
  +the OpenAPI specification for Stripe.
  +
  +To update the generated code, use the included scripts:
  +
  +```sh
  +# Generate files into the ./openapi/out directort (working directory must be project root)
  +> ./openapi/build
  +
  +# Copy reviewed files to ./src/resources
  +> ./openapi/commit
  +```
  