This commit moves the tooltip into example-wrap, simplifying allowing several
overly-complex things to be fixed:
* The mousover javascript can be removed, because hovering example-wrap can
style the tooltip inside.
* The sibling selecor can be removed, because hovering the tooltip also
hovers the wrapper, which can hover the codeblock itself.
* The relative positioning of the `<li>` tag, which was added in
e861efd9f9 to fix the positioning of the code
tooltip, can now be removed, because example-wrap itself already has
relative positioning.
