Documentation for adding Dropzone to Final Form

Struggling to understand how I include a third party component such as `react-dropzone` into `react-final-form`. I found some other issues relating to this on here, but they seem to be referring to older versions of final form and dropzone, so they don't seem to help.

[I posted on SO](https://stackoverflow.com/questions/57483296/using-react-dropzone-together-with-react-final-form) with a [non working code sandbox](https://codesandbox.io/s/sweet-meitner-6yde6). I would very much appreciate a basic example with working dropzone integration if possible.