gruntplugin README boilerplate improvements

@cowboy

The gruntplugin scaffolding is awesome but there is a problem with the README.
I have seen many complaints about this in the Grunt community and stumble over this issue myself a lot.

Most gruntplugin README start with this at the top:

> # Getting Started
>
> This plugin requires Grunt ~0.4.0
>
> If you haven't used Grunt before, be sure to check out the Getting Started guide, as it explains how to create a Gruntfile as well as install and use Grunt plugins. Once you're familiar with that process, you may install this plugin with this command:
>
> npm install grunt-contrib-compass --save-dev
> Once the plugin has been installed, it may be enabled inside your Gruntfile with this line of JavaScript:
>
> grunt.loadNpmTasks('grunt-contrib-compass');

I find this confusing because I would like to see what the plugin does at the top of the README. I would also argue that most people who look for gruntplugins know what Grunt is. So just a link to the Grunt site would suffice.

It would also be great if the README would try to encourage MORE documentation of the gruntplugin and even screenshots and screencasts if suitable.

Thoughts?