Review handling of URLs in the post body

I'm receiving an "INVALID_DOCUMENT" error when publishing various posts. Attached is the JSON. I was unable to see anything specifically wrong with the document.

[article-2692.zip](https://github.com/alleyinteractive/apple-news/files/214080/article-2692.zip)
