Create well-known-uri.md

[simonwfarrow]

specification for submission to https://github.com/protocol-registries/well-known-uris

[jph00]

Thanks for this. The llms.txt file actually has a more specific format than just being arbitrary markdown, which is described on the site, and can be tested by using the python module provided. llms-ctx.txt then is the same file, but with the URLs expanded to include the contents, but not including the 'optional' section. llms-ctx-full.txt includes the 'optional' section.