Update tutorial.md - adding the line for the jsx 

Adding `/** @jsx React.DOM */` to the tutorial code snippets so that when copy pasted, the jsx transformer can convert it to javascript
Nit: all of these are usually the first thing in a block, indicating the filename. We might want to just get rid of them (cc @petehunt)

But also, when adding lines you need to update the highlights we have set (that the `{6-8}` in the opening of the code fence)