Example usage update

[mderrick]

This might be my stupidity but I think the example readme should mention you need to run npm install in the parent directory for it to work.

OR preferably we update the example package.json to include this repo as a dependency and use it as it would be used in the real world:

"jest" : {
    "moduleLoader": "<rootDir>/example/node_modules/jest-webpack/ModuleLoader"
},
{
    "devDependencies": {
        "jest-webpack": "git+ssh://git@github.com:60frames/jest-webpack.git#master"
    }
}

[richardscarrott]

https://github.com/60frames/jest-webpack/commit/d5831acb536cf11ed9145d62bef53a3642336273