There now is documentation for how Web Concepts are made available as JSON data. The JSON documentation provides an overview of how Web Concepts are made available as two general JSON documents: Specification data and concept data.
The documentation for specification data describes how the specifications available from the specifications page are represented as a JSON document.
The documentation for concept data (concepts and values) describes how concepts and concept values available from the concepts page are represented as a JSON document.
I hope this documentation help to make Web Concepts easier to use, and as usual, please provide feedback if you have any questions or comments.