Encore Framework docs

The Encore Framework's docs needed a facelift! We added permalinks with icons that show on hover, a new style for stability badges, and better examples with a "Do/Don't" area. We also implemented more of Prism's code styles (zebra striping and line numbers) to make it easier for developers consuming our documentation to discuss the code. We also added a sliding accordion effect so that code snippets can be expanded to their full height, instead of forcing users to scroll in a small area.