Suggest better default for prometheus port

Reserved port[1] is now suggested

Fixes #86

[1]: https://github.com/prometheus/prometheus/wiki/Default-port-allocations

main.go

@@ -53,7 +53,7 @@ var apiQueueLimit = flag.Uint("apiQueueLimit", 0, "Number of API requests allowe
 var apiQueueTimeout = flag.Duration("apiQueueDuration", queueing.DefaultTimeout, "Maximum queueing duration of requests")
 var apiCiLongPollingDuration = flag.Duration("apiCiLongPollingDuration", 0, "Long polling duration for job requesting for runners (default 0s - disabled)")
 var logFile = flag.String("logFile", "", "Log file to be used")
-var prometheusListenAddr = flag.String("prometheusListenAddr", "", "Prometheus listening address, e.g. ':9100'")
+var prometheusListenAddr = flag.String("prometheusListenAddr", "", "Prometheus listening address, e.g. 'localhost:9229'")
 func main() {
 	flag.Usage = func() {