Merge branch 'kube-prometheus_documentation' of https://github.com/jolson490/prometheus-operator into kube-prometheus_documentation

Resolves issue #1629 in this repository.

Prune/jsonnet namespace roles

*/README.md: Include 'Contributing' section

By default if a new object (servicemonitor, secret, ...) is created /
updated / deleted, we reconcile all Prometheus instances in that
namespace. In addition we also need to reconcile all Prometheus
instances selecting objects (ServiceMonitors, PrometheusRules) in that
namespace.

Resolves issues #1571 and #1609 in this repository.

Merge remote-tracking branch 'origin/prune/jsonner-namespace-roles' into prune/jsonner-namespace-roles

replaced default namespaces rbac rules by a loop


set right variable name

Change-Id: I589eb7b007f9ac035936c95eaa818497607038bc

Change-Id: I54f6f26449b0f16b7be2f202ec93e7c29a377108

Change-Id: I85f679ea7a33febf5d730960bf754f4b459f53d3

adjust rbac apiGroups to support core workloads api apps/v1

Without this access the logs of metrics-server will show the following error line:
```
unable to fully scrape metrics from source kubelet_summary:k8s-1: unable to fetch metrics from Kubelet k8s-1 (10.8.10.14): request failed - "403 Forbidden", response: "Forbidden (user=system:serviceaccount:kube-system:metrics-server, verb=get, resource=nodes, subresource=stats)",
```
and `kubectl top nodes` will give no results