4.1: How to connect battery?

As mentioned on this page, you can use a 3S LiPo battery to power the Jetson TK1 directly, so for example, you could cut off the connector on your LiPo battery pack and attach a standard 2.1mm DC power barrel connector (available from any Radio Shack or Fry's or online "http://www.pololu.com/product/2448", etc). But I forgot to mention on the page that the center-pin is positive and the outer ring is negative. (I've added it just now, thanks!). If you think the current Wiki page does not explain this properly then feel free to tell me how it should be explained and I'll consider updating the instructions.