Update deprecation notice.

[lgarron]

It now:

• Links to the built-in JSON parsing functions on MDN (which contain explanations, examples, and links to specs).
• Contains an obvious example that is ready to copy, with some conveniences and guiderails. In particular:
  • Avoids top-level await (which is well-supported by browsers but still errors in TypeScript unless you specifically configure it).
  • Includes TypeScript annotations to help make it easy to use the code without hacks.
• Provides encouragement and rationale to stop using @github/webauthn-json.
• Includes a fallback example, both as a pragmatic compromise but also to illustrate the tradeoffs vs. completely moving off the library.

[lgarron]

• Uses JSDoc comments which ensure that the functions receive the correct types in TypeScript, while still allowing the code to be pasted into vanilla JS.

Wait, this part is not being picked up properly by TypeScript. Lemme fix that.

[lgarron]

• Uses JSDoc comments which ensure that the functions receive the correct types in TypeScript, while still allowing the code to be pasted into vanilla JS.

Wait, this part is not being picked up properly by TypeScript. Lemme fix that.

Looks like this is not possible, since apparently JSDoc annotations are ignored in .ts files. So the example will fail TypeScript checking in either JS or TS unless I complicate the code in a way that makes it even harder to understand. So I've just converted it fully to TS and added a comment at the top of the example snippet.