Adding the link makes sense to me. Adding all the macros definition to the wiki does not make sense to me, but form different reasons. I think that having %py3_build_egg and %py3_install_egg there is just not necessary. Since there are more files at [0] I'd just add that link.
[0] https://src.fedoraproject.org/rpms/python-rpm-macros/tree/ma ster
About flit:
* is this way of creating Python distributions getting more and
more popular?
* if so, should we add a new section of the guidelines? something like
"Packaging setup.py-less projects"?