Found a couple of good links that have some decent information on Markdown (though which flavor is up for grabs):

• Markdown code block - supported languages?
• CodeMirror - language mode some good ones here. A couple that I like, in particular:
  • diff
  • shell (what I would suppose is bash)
  • yaml
• MacDown supported Syntaxes
• Syntax highlighting in markdown - has a lot of the common extensions that you can use for each one, though it is 4 years old.