Lacking documentation, some notes:

• To delete a listing that used a filter, I also had to edit wcagver in _policies/js/script.js. Here's the pull request 403. I suspect when we add WCAG 2.1, we might also need to add to this file?
• Some policy code elsewhere: https://github.com/w3c/wai-website-theme/blob/master/_includes/multilang-list-policy-links.html & https://github.com/w3c/wai-website-theme/blob/master/_includes/multilang-policy-title.html