Fixed comment on wrong line.

While investigating and fixing an issue on our 1.5.1 branch,
I saw you also/already fixed the bug I found (tags not updated
for existing servers), but comment is misplaced.

agent/router/serf_adapter.go

@@ -67,9 +67,10 @@ func HandleSerfEvents(logger hclog.Logger, router *Router, areaID types.AreaID,
 			case serf.EventMemberFailed:
 				handleMemberEvent(logger, router.FailServer, areaID, e)
 
-			// All of these event types are ignored.
 			case serf.EventMemberUpdate:
 				handleMemberEvent(logger, router.AddServer, areaID, e)
+
+			// All of these event types are ignored.
 			case serf.EventUser:
 			case serf.EventQuery: