Outdated "ChanServ welcome notices in appropriate channel buffer" wiki section

[vyp]

The wiki still says to use circe-add-message-handler, but it was removed in d8cd635. So I guess this section needs to be updated to use the irc event handlers system, but I don't know how, hence this issue.

cc @retroj since it seems like you added this wiki section in the first place, in case you still use circe. If not, of course feel free to unsubscribe from this. :)

[jorgenschaefer]

Nice catch! (Pesky documentation, always getting outdated! :-D)