The example are in a layout so "float:right" doesn't have an effect in that div
Instread, just put the preview inside the example.
This also remove the "Preview:" text
rustdoc changed the html generated. The code used to be in a `<code>`, now it is
in a `<pre>`
So this should wotk with both stable rust and nightly rust
Instead of repeating the table of contents, provide a proper intro
page - based on the Github README - and group the remaining content
into Getting Started, Reference and Integration sections.
