Make syntax highlighting on github.com work

Howdy, @Ball. I did some code spelunking, and found that it was pretty easy to make syntax highlighting work. I don't know what this'll do to the parser.

[rendered embergo.md](https://github.com/Ball/moirai/blob/4f4b4444b1a47950080aa7c69988d1e64bbe17b7/examples/Embergo.markdown)