Kubernetes SD: More fixes to example config
Kubernetes SD: More fixes to example config

- Avoid mentioning the `in_cluster` option. (It doesn't exist anymore.)
- Replace `__meta_kubernetes_service_namespace` and
  `__meta_kubernetes_pod_namespace` (which don't exist anymore) by
  `__meta_kubernetes_namespace`.

PrFalken/prometheus,Gouthamve/prometheus,amorken/prometheus,alileza/prometheus,amorken/prometheus,GoogleCloudPlatform/prometheus,prometheus/prometheus,AlekSi/prometheus,Gouthamve/prometheus,tomwilkie/prometheus,datajet-io/prometheus,Colstuwjx/prometheus,Conorbro/prometheus,JavierZunzunegui/prometheus,kzittritsch/prometheus,datajet-io/prometheus,Conorbro/prometheus,yanghongkjxy/prometheus,agaoglu/prometheus,kzittritsch/prometheus,kangwoo/prometheus,Colstuwjx/prometheus,amorken/prometheus,slok/prometheus,alileza/prometheus,AlekSi/prometheus,prometheus/prometheus,AlekSi/prometheus,PrFalken/prometheus,Stackdriver/stackdriver-prometheus,dsymonds/prometheus,slok/prometheus,Colstuwjx/prometheus,SaltedMan/prometheus-annotated,kangwoo/prometheus,brancz/prometheus,Stackdriver/stackdriver-prometheus,Gouthamve/prometheus,GoogleCloudPlatform/prometheus,dsymonds/prometheus,keegancsmith/prometheus,Stackdriver/stackdriver-prometheus,tomwilkie/prometheus,tomwilkie/prometheus,alileza/prometheus,kzittritsch/prometheus,Conorbro/prometheus,gottwald/prometheus,GoogleCloudPlatform/prometheus,dsymonds/prometheus,slok/prometheus,agaoglu/prometheus,datajet-io/prometheus,yanghongkjxy/prometheus,datajet-io/prometheus,prometheus/prometheus,alileza/prometheus,JavierZunzunegui/prometheus,alileza/prometheus,gottwald/prometheus,prometheus/prometheus,agaoglu/prometheus,kangwoo/prometheus,kzittritsch/prometheus,GoogleCloudPlatform/prometheus,Colstuwjx/prometheus,PrFalken/prometheus,keegancsmith/prometheus,prometheus/prometheus,JavierZunzunegui/prometheus,Stackdriver/stackdriver-prometheus,GoogleCloudPlatform/prometheus,keegancsmith/prometheus,JavierZunzunegui/prometheus,keegancsmith/prometheus,brancz/prometheus,slok/prometheus,kangwoo/prometheus,tomwilkie/prometheus,brancz/prometheus,SaltedMan/prometheus-annotated,SaltedMan/prometheus-annotated,yanghongkjxy/prometheus,amorken/prometheus,Conorbro/prometheus,Gouthamve/prometheus,gottwald/prometheus,agaoglu/prometheus,yanghongkjxy/prometheus,dsymonds/prometheus,gottwald/prometheus,keegancsmith/prometheus,brancz/prometheus,SaltedMan/prometheus-annotated,PrFalken/prometheus,AlekSi/prometheus