Import definitions from Reffy data

[dontcallmedom]

reffy supports extracting definitions from specs identified as browser specs and publishes its extracts as JSON data.

These definitions cover a broader set set of specifications and extract them daily from the latest editors draft (including for ReSpec documents), with around 20K more definitions identified in the process (see a more detailed comparison with Shepherd data.

If needed, the index of all specifications crawled for definitions is available in a JSON file, along with metadata about each specification. The list and metadata directly come from browser-specs.

(beyond my involvement in reffy, getting this done would also be very useful to me as a spec contributor since a number of WebRTC specs are stuck in terms of using auto-links due to outdated data in the Shepherd data)

/cc @tidoust

[dontcallmedom]

this would also address #1756 & #1664

[dontcallmedom]

@tabatkins is there anything @tidoust or I could do to help on this?

[jyasskin]

Per https://lists.w3.org/Archives/Public/spec-prod/2023JanMar/0004.html, I think this is finished. 🎉