[documentation] New IRC channel for docs

[Addison Berry]

Hey folks, we now have a new channel for documentation brainstorming,  
#drupal-docs on freenode. There was a lot of good discussion started  
at the docs sprint in Boston today and so thanks to chx, we have a  
channel to keep it going. We decided on adding the channel vs relying  
solely on the mailing list and queue because a small group of us want  
to be able to have some online meetings where we can hash things out  
real time. Feel free to join whenever and talk shop.

- Addi (add1sun)