Add join/part/quit filtering example

I don't care that this looks nuts.

catgirl.1

@@ -570,6 +570,11 @@ Configuration file:
 host = chat.freenode.net
 join = #ascii.town
 .Ed
+.Pp
+Filtering joins, parts and quits from a channel:
+.Bd -literal -offset indent
+ignore = * [JPQ][OAU][IR][NT] #example
+.Ed
 .
 .Sh STANDARDS
 .Bl -item