Cheat sheet

Hi Joe,

First, I had some trouble building the project, I found using "npm i -d" installs the dependencies such as express and its sub-dependencies and then everything works like magic. I've made that little modification to the instructions as such.

The thing I wanted to add was the cheat sheet. When I first tried Dillinger, I opened it up and pasted in my existing markdown, but then realised I couldn't remember how what the formatting should go like. I thought there might be some help and I clicked Utilities, but I didn't what I wanted. I thought instead of just tweeting you, I'd try a quick patch myself. It displays another menu item that takes you to [this cheatsheet](https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet) on GitHub.

Cheers,
George