Fixes #632 - fixes incorrectly nested paragraph

- Fixes #632 - fixes incorrectly nested paragraph. The paragraph
element containing the “More info…” link was inside the definition list
when it should be outside of it.
- Also adds some code comments for method parameters in the
info_box_helper methods for use by the yard gem.
Have you tested this in the browser? I think you're missing `html` in the return statement because nothing would be returned if there is no URL. Also, I would prefer `if` instead of `unless` (it requires less thinking):
`return html if info_box['url'].blank?`