gpg(1) says:
dane Locate a key using DANE, as specified in draft-ietf-dane-openpgpkey-05.txt.
But that draft has long since been superseded by the official RFC 7929. If gpg supports the version released in the RFC, the documentation should state it. If it does not support it because of changes in the specification since draft -05, we probably need to fix gpg to follow RFC 7929.