Update docs to avoid UnrecognizedKwargsError error

[brunopoeta]

I stumbled into this issue on Friday and found two messages on OpenAI's community related to it (both without a clear resolution)

https://community.openai.com/t/getting-strange-unrecognizedkwargserror-error/169600
https://community.openai.com/t/unrecognizedkwargserror-error/197313

After checking the example repo, most specifically the openapi.yaml file, I've noticed that you need to explicitly declare the parameters that are going to be sent to the plugin's API endpoint, and after adding them, the issue went away.

OpenAPI definition documentation

Ideally, it should have one more example showing parameters being declared, just like the example repo.