[PATCH] HACKING GUIDE: IRC address and freenode webchat client addition

[[[

Add information about svn-dev IRC channel.

* community-guide/general.part.html:
   (participating): Add IRC address and freenode webchat client.

]]]

Notes:

-<p>Go to <a href="http://subversion.apache.org/"
->http://subversion.apache.org/</a> and</p>

was removed with the reasoning that:

a) they are already here (and where we'd like them to be)

b) we want them to look at the links in this section and not wander off
to get lost.

I've set the user name to 'visitorNNN' so we know they came through the
HACKING GUIDE.

Gabriela