Documentation changes

Hi Jan

It's been ages since I did any coding with node & xbee.  I can see you've been taking things further and further - great stuff, and well done for sharing with the world.

I'm thinking about a new project and thought why not use your newest stuff (xbee-api, right?) from the beginning.

Here are two tiny things that I think you should update in the example docs.

I'll try and send more pull requests if I can suggest anything else.

Best regards,

Richard