Add basic example to README

Was checking out animate.css, which is pretty cool btw and figured it'd be cool to a have a really basic usage guide for beginners. 
Hope it's usefull :heart: :smile: 

+1 to this addition.  Furthermore, basic usage should be included in the `index.html` file of the `gh-pages` branch so it appears [http://daneden.github.io/animate.css/](http://daneden.github.io/animate.css/) as well.