Fix full JSON example

This took me a long while to figure out, but I think the JSON example needs some tweaking to make it the equivalent of the XML example. In the XML example, it looks like this (condensed):

```xml
<uber version="1.0">
  <data rel="self" url="http://example.org/" />
  <data rel="profile" url="http://example.org/profiles/people-and-places/" />

  <data id="people" rel="collection http://example.org/rels/people" url="http://example.org/people/">
  </data>
</data>
```

The JSON variant is this (also condense, with comment to point out issue):

```javascript
{
  "uber" :
  {
    "version" : "1.0",
    "data" :
    [
      {"rel" : ["self"], "url" : "http://example.org/"},
      {"rel" : ["profile"], "url" : "http://example.org/profiles/people-and-places"},

      {
        // Note this data element
        "data" :
        [
          {
            "id" : "people",
            "rel" : ["collection","http://example.org/rels/people"],
            "url" : "http://example.org/people/",
            "data" : []
          }
        ]
      }
    ]
  }
}
```

The item noted above makes for an extra, empty data element, which would be this in XML:

```xml
<uber version="1.0">
  <data rel="self" url="http://example.org/" />
  <data rel="profile" url="http://example.org/profiles/people-and-places/" />

  <data>
    <data id="people" rel="collection http://example.org/rels/people" url="http://example.org/people/">
    </data>
  </data>
</data>
```

This pull request removes that extra data element. It's very hard to see without working with some code that is implementing this. To see the results in Hyperdescribe, view the [example in the repo](https://github.com/smizell/hyperdescribe-hal-json/blob/c849bffc63ee0ffabe2bad953ffe86bf23e94b45/examples/source.hyperdescribe.js).

Hope this makes sense. **Please check me to make sure I got this right!**