Added a .data(obj) example

The documentation was missing this example. So now the code block looks like this:

```javascript
$('body').data('foo', 52);
$('body').data('bar', { myType: 'test', count: 40 });
$('body').data({ baz: [ 1, 2, 3 ] });

$('body').data('foo'); // 52
$('body').data(); // {foo: 52, bar: { myType: 'test', count: 40 }, baz: [ 1, 2, 3 ] }
```