Make sure the normalized markdown is compatible with elm-markdown

http://package.elm-lang.org/packages/evancz/elm-markdown/latest is what's used on package.elm-lang.org. So the normalized markdown needs to cause no ambiguities with that engine.

Comparison tool: https://johnmacfarlane.net/babelmark2/

Possibly use the marked js library in integration tests to verify things.

Start by comparing the normalized output against elm-markdown using the linked Babelmark2 comparison tool. Investigate whether marked can be used in integration tests, and define done as normalized Markdown producing unambiguous, compatible results in the target engine.

Written by the indexing model from the issue text.