Sylvia/docs/doc 1105

@lamagnifica @catong @mhoeber: This is a draft of the updates to the Register Your Account section to reflect the new login/registration page. The feature is currently in a/b testing, so we don't want to merge the branch yet, but feedback is still welcome.
I agree. Mostly I updated the text because it was in there before, but I was having second thoughts. It doesn't really serve a purpose and we have no way of knowing when it will be updated, though, so I can take it out.