References are rendering weirdly

[billbrod]

While numpydoc supports a dedicated references section, mkdocstrings does not. The advice is to use footnotes to get something similar, but we've struggled to get them working correctly. In particular, the footnote itself renders correctly, but not the link to it (and thus, not the link back). Should poke around and see if there's something wrong with our configuration that's messing this up. An alternative would be annotations, but I think that isn't a perfect replacement (in particular, it doesn't work well when you have multiples citations to the same reference)