We aren't seeing an option to turn an existing article into a category. When we add content to that should be a child to the initial article, we have to:
  1. Create a new category article
  2. Copy the content from the original article to the new category article.
  3. Change the slug of the initial article.
  4. Copy the slug of the initial article to the new category article.
  5. Delete the original article.
  6. Add pages beneath the category as needed.
It'd be great to have an option in the article options to make an article a category instead.