fix busybox image to 1.28 (issues with nslookup).

Changes where done with these commands:

reprec 'image: busybox(?!:)' 'image: busybox:1.28' */docs */examples
reprec -- '--image=busybox(?!:)' '--image=busybox:1.28' */docs */examples

Related issues:

 https://github.com/docker-library/busybox/issues/48
 https://github.com/kubernetes/kubernetes/issues/66924

content/en/examples/admin/logging/two-files-counter-pod-agent-sidecar.yaml

@@ -5,7 +5,7 @@ metadata:
 spec:
   containers:
   - name: count
-    image: busybox
+    image: busybox:1.28
     args:
     - /bin/sh
     - -c

content/en/examples/admin/logging/two-files-counter-pod-streaming-sidecar.yaml

@@ -5,7 +5,7 @@ metadata:
 spec:
   containers:
   - name: count
-    image: busybox
+    image: busybox:1.28
     args:
     - /bin/sh
     - -c
@@ -22,13 +22,13 @@ spec:
     - name: varlog
       mountPath: /var/log
   - name: count-log-1
-    image: busybox
+    image: busybox:1.28
     args: [/bin/sh, -c, 'tail -n+1 -f /var/log/1.log']
     volumeMounts:
     - name: varlog
       mountPath: /var/log
   - name: count-log-2
-    image: busybox
+    image: busybox:1.28
     args: [/bin/sh, -c, 'tail -n+1 -f /var/log/2.log']
     volumeMounts:
     - name: varlog

content/en/examples/admin/logging/two-files-counter-pod.yaml

@@ -5,7 +5,7 @@ metadata:
 spec:
   containers:
   - name: count
-    image: busybox
+    image: busybox:1.28
     args:
     - /bin/sh
     - -c