Merge pull request #2672 from svend/kubernetes-pods-port-comment

Document what ports are scraped by default in k8s example

documentation/examples/prometheus-kubernetes.yml

@@ -158,7 +158,8 @@ scrape_configs:
 #
 # * `prometheus.io/scrape`: Only scrape pods that have a value of `true`
 # * `prometheus.io/path`: If the metrics path is not `/metrics` override this.
-# * `prometheus.io/port`: Scrape the pod on the indicated port instead of the default of `9102`.
+# * `prometheus.io/port`: Scrape the pod on the indicated port instead of the
+# pod's declared ports (default is a port-free target if none are declared).
 - job_name: 'kubernetes-pods'
 
   kubernetes_sd_configs: