Improve IRC service documentation

It wasn’t clear to me how to _enable_ colors in messages, so I figured that out, and documented it.  Once I started writing, the whole thing just rewrote itself. Additionally:

- Updated default SSL port, following https://github.com/github/github-services/commit/cfecb177c41cf76b44b939080ad25660f4b5d496.
- Replaced stale information about branch regexes, following https://github.com/github/github-services/commit/5df8a1b0b71b1722fe280a20734f89b0219e4882.

cc @kdaigle, @atmos