Added missing documentation entries for attributes on DataConnection obj...

...ect. Sorted alphabetically.

I tried to come up with accurate descriptions for the missing attributes, let me know if any of these need to be edited. I realize they aren't the best.

How do you feel about sorting the definitions alphabetically? Most browsers display them in this order when they are inspected, it's nice to have them match.

Since all of the attributes contained within <code>.options</code> are pushed up a level and have their own dedicated space within <code>DataConnection</code>, should we maybe it this private? As it stands, there is more than one way to snag the same piece of data - which seems odd to me. Thoughts?

*In response to your comment about <code>.pc</code> being changed to <code>.peerConnection</code>:*

Agreed! Do you think using <code>.dataChannel</code> instead of <code>.dc</code> was a mistake? I'm worried that if we change <code>.pc</code> at this stage in the game we may introduce errors for people consuming the library. I'm unaware of a reason for accessing the RTCPeerConnection object directly - do you think anyone is making use of <code>.pc</code> and how worried about this are you?

I'll keep an eye out for more improvements to the documentation. I think you've done a fantastic job with it thus far!