Consider swapping "nonbinary" language for "gender-non-conforming"

[patcon]

Re-ticketed from https://github.com/ajdavis/twitter-gender-distribution/pull/32

Realized that while nonbinary suits all of these (verifiable via on Nonbinary Wiki, gender-non-conforming might be more clear, since:

[...] nonbinary is an umbrella term itself, although some people use it to describe their specific gender identity too.

But of course, perhaps people with lived experience should comment on this. Happy to try to loop some folks in, if you're open to conversation :)