Need to change a text on the demo page.

On the third line of Demo page (http://rwdgrid.com/demo/) there is an inconsistency on the content of second grid.

The grid is: 

```
<div class="grid-10">
  <p> grid 12 </p>
</div>
```

And should be:

```
<div class="grid-10">
  <p> grid  10 </p>
</div>
```

I think this sounds a little confusing.
