gender element, attributes, modifications of sex and gender for #2189 and #2190

[ebeshero]

@sydb We've made several changes in response to your review and we may now be ready to merge this in to dev (you're the one we assigned for this!) NOTE: I've added some short but significant revisions to our discussion of characteristics/traits in the ND chapter while working on the PR this weekend, mainly to revise some strange things and provide a little more commentary specific the challenges we face as text encoders of documents from times and places not our own. I hope it's all good!

[ebeshero]

@martinascholger @sydb I think we're now up-to-date with responding to all the revision requests. Are we ready to merge this branch to dev?

[sydb]

I am not remotely convinced this is perfect. I reasonably convinced it is good enough to be part of the Guidelines proper, and be tweaked in dev as needed.

[sydb]

BTW —

• Passed all tests in my local Docker environment.
• I used a squash-and-merge, so we may not want to delete the branch for a bit.