Update documentation based on GET /fills deprecation notice

[mchalise]

There's a giant deprecation notice for the GET /fills endpoint https://docs.gdax.com/#fills

The README on this project needs to be updated to have an example of how to pass in the product_id or order_id.

Coinbase::Exchange::BadRequestError: {"message":"query must contained either product_id or order_id"}

I am getting this error.

[mchalise]

GET /products

Will provide product ids. But I am now confused on how to do pagination any idea?

[drewrothstein]

Hi, we are closing out PRs + Issues as this project is being archived.