Automatic merge from submit-queue

Add note: kubelet manages only k8s containers.

Kubelet wrote log when accesing container which was not created in k8s, what could confuse users. That's why we added note about it in documentation and lowered log level of the message to 5.

Here is example of the message: 
```
> Apr 19 11:50:32 openshift-114.lab.sjc.redhat.com atomic-openshift-node[9551]: 
I0419 11:50:32.194020    9600 docker.go:363] 
Docker Container: /tiny_babbage is not managed by kubelet.
```

bug 1328441
Bugzilla link https://bugzilla.redhat.com/show_bug.cgi?id=1328441