Use a non-standard port for the DD example (#242)

Co-authored-by: Tyler Yahn <[email protected]>

Author: jmacd

exporters/metric/datadog/datadog.go

@@ -54,7 +54,7 @@ func NewExporter(opts Options) (*Exporter, error) {
 // Options contains options for configuring the exporter.
 type Options struct {
 	// StatsAddr specifies the host[:port] address for DogStatsD. It defaults
-	// to localhost:8125.
+	// to DefaultStatsAddrUDP.
 	StatsAddr string
 
 	// Tags specifies a set of global tags to attach to each metric.

exporters/metric/datadog/example_test.go

@@ -39,15 +39,17 @@ type TestUDPServer struct {
 }
 
 func ExampleExporter() {
+	const testHostPort = ":8159"
 	selector := simple.NewWithSketchDistribution(ddsketch.NewDefaultConfig())
 	exp, err := datadog.NewExporter(datadog.Options{
+		StatsAddr:     testHostPort,
 		Tags:          []string{"env:dev"},
 		StatsDOptions: []statsd.Option{statsd.WithoutTelemetry()},
 	})
 	if err != nil {
 		panic(err)
 	}
-	s, err := getTestServer(datadog.DefaultStatsAddrUDP)
+	s, err := getTestServer(testHostPort)
 	if err != nil {
 		panic(err)
 	}