docs: document responders for hyphenated HTTP methods

[mvanhorn]

Summary of Changes

Falcon resolves responders by looking up on_<method> attributes on a resource. That means a responder for an HTTP method whose name contains a hyphen or other non-alphanumeric character (for example a WebDAV-style VERSION-CONTROL method) cannot be written as an ordinary method, because on_version-control is not a valid Python identifier. This is a real but rare limitation, and the maintainers confirmed in the thread that no routing code change is warranted.

Both vytas7 and CaselIT converged on a documentation-only resolution: explain the limitation and show the supported workaround. The agreed workaround is to register the responder imperatively with setattr(resource, 'on_version-control', handler), which the existing attribute-based dispatch picks up at request time exactly as it would for a normally-named responder.

This change adds a short note to the routing docs describing the limitation and that workaround, keeping the example minimal and consistent with the surrounding Google-style docs. It also adds a 2647.misc.rst towncrier news fragment. No runtime routing or dispatch code is touched, matching the maintainers' stated decision in the issue.

Related Issues

Closes #2647

Pull Request Checklist

• Applied changes to both WSGI and ASGI code paths and interfaces (where applicable) — n/a, documentation only and the limitation is shared by both
• Added tests for changed code — n/a, documentation only
• Performed automated tests and code quality checks — n/a, no code changed
• Prefixed code comments with GitHub nick and an appropriate prefix — n/a, no code comments added
• Coding style is consistent with the rest of the framework
• Updated documentation for changed code
• Added a towncrier news fragment under docs/_newsfragments/ (2647.misc.rst)
• LLM output has been carefully reviewed and tested by a human developer

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (370f933) to head (094df54).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

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  Files           64        64           
  Lines         7985      7985           
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  Hits          7985      7985           

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[CaselIT]

Prose is fine, just a minor note on the example code

[CaselIT]

I would dp this on the class instead

[mvanhorn]

Done in 094df54. Moved the setattr onto the class and verified the example end to end: a VERSION-CONTROL request against the snippet resolves the responder and returns 200.