added irc channel to README

I'm available in the channel about 12 hours per day, and eventually others will probably join who are willing to help out.

IRC's good for reducing the number of "How do I do this?" issues created, and helping people quickly.  I've been giving support for various software/languages/frameworks in IRC for 6 years, and it's great.

Can also be used for things like "Is this bug reported already?" and quick brainstorming about ideas/implementation.