[ietf-dkim] Internationalized domain names

[Paul Hoffman]

Eric added the following to base-04:
        Internationalized domain names MUST be punycode-encoded
        [RFC3492].
This is very wrong. The Punycode encoded value does not include the 
"xn--" string.

The text should instead read:
        Internationalized domain names MUST be converted using
        the  steps in section 4 of [RFC3490] using the ToASCII
        function.