collate reference list

[juniperlsimonis]

include a reference/reading list of documents detailing the underlying concepts let's start pulling them together here

@kswhitney

https://arxiv.org/abs/1907.04893 https://civic.mit.edu/2016/06/03/a-primer-on-non-binary-gender-and-big-data/ [note: incorrect/outmoded separation of sex and gender]