Add note on irssi including set up and configuration

`irssi -c`
`irssi -h`
`irssi -n`
`irssi -p`
`irssi -v` prints the version info
`irssi -w`

it apparently has no uppercase option flags. I did not look to see if theres any -- option flags yet.

/etc/irssi.conf is one config file

~/.irssi/config is the other config file

To add a new server..
/server add -auto -network NetworkName irc.example.com 6667

To connect to the new server..
/connect NetworkName

settings in ~/.irssi/config are usually `settings.get` followed by whatever setting.