Merge branch 'master' of https://github.com/kubernetes/kubernetes.github.io into release-1.6

* 'master' of https://github.com/kubernetes/kubernetes.github.io:
  Update some description about secrets
  [Federation] Add a note about DNS API scopes to the Federation tutorial (#2943)
  Delete the useless spaces in html files
  Fix typo
  update resource-usage-monitoring.md

docs/user-guide/secrets/index.md

@@ -789,8 +789,6 @@ Pod level](#use-case-secret-visible-to-one-container-in-a-pod).
    run a pod which exposes the secret.
  - If multiple replicas of etcd are run, then the secrets will be shared between them.
    By default, etcd does not secure peer-to-peer communication with SSL/TLS, though this can be configured.
- - It is not possible currently to control which users of a Kubernetes cluster can
-   access a secret.  Support for this is planned.
  - Currently, anyone with root on any node can read any secret from the apiserver,
    by impersonating the kubelet.  It is a planned feature to only send secrets to
    nodes that actually require them, to restrict the impact of a root exploit on a