Improve documentation / provide llms.txt file

Hi, thank you for all your excellent APIs! They are great.

Unfortunately the documentation is a bit lacking. The interactive code builder is a bit buggy (the API request body doesn't change when you toggle the settings), and it's difficult to get a clear sense of the response payload body shape. Could you please provide clear documentation for the APIs, perhaps in the form of llms.txt, so that I can more easily integrate these systems?

Start by reviewing the interactive code builder and the current API documentation, focusing on the request-body toggle behavior and the response payload shapes. Done should include clearer API documentation and an llms.txt file, with the builder behavior addressed if it is within scope.

Written by the indexing model from the issue text.