Minor documentation fix

prometheus/doc.go

@@ -60,7 +60,7 @@
 //    	// The Handler function provides a default handler to expose metrics
 //    	// via an HTTP server. "/metrics" is the usual endpoint for that.
 //    	http.Handle("/metrics", promhttp.Handler())
-//      log.Fatal(http.ListenAndServe(":8080", nil))
+//    	log.Fatal(http.ListenAndServe(":8080", nil))
 //    }
 //
 //