added paper docs for wrapped content

[ninjasort]

No description provided.

[hai-cea]

Thanks @cameronjroe - I think a better way to illustrate that developers can put content inside the Paper Component is to actually put content in the examples.

Maybe putting the zDepth inside each box?

For example:

<Paper zDepth={1}>
  <p>zDepth=1</p>
</Paper>
<Paper zDepth={2}>
  <p>zDepth=2</p>
</Paper>
... etc

[hai-cea]

Thanks @cameronjroe - looks great.