Add a "See Also" section, linking to the RFC

[alexgloverl]

It might be nice to have a SEE ALSO section in the statcode output, linking to the relevant section of the RFC that "governs" the status codes. Some of the descriptions there are more extensive than those you have here, but unfortunately the license doesn't allow for just taking them from there. For example for 101, there'd be:

SEE ALSO
    RFC 7231 — §10.1.2, 101 Switching Protocols <https://tools.ietf.org/html/rfc2616#section-10.1.2>

(Just an idea.)