update examples to be easier to play with

- Create index file to list all of the examples
- Normailize headers of all examples to include link back to example list
- Always include the global.css in all examples
- Change examples to target `<div id="example"/>` instead of `document.body`
- Fix the CSS of some examples not happy about sharing the page
- Include a README to explain how to make the examples
- Move animation example's inline css into a separate file to match other examples