Any documentation about the different formatter options

Is there an API or existing exhaustive documentation off the formatter options?

Looking at the [hexdocs for `ESpec.Formatters.Doc` module][hex], `format_example`, `format_result` and `init` all appear to support options (through `opts`) but there's no documentation there about which options. The only documentation to suggest any options is in the README [under Formatters][formatters] mentioning the `diff_enabled?` and `out_path` options.

Have I missed another source of documentation or is that all the documentation available about supported formatter options for each built-in formatter?

[hex]: https://hexdocs.pm/espec/ESpec.Formatters.Doc.html
[formatters]: https://github.com/antonmi/espec/blob/master/README.md#formatters