Move Guide toic to Tasks: kubectl exec.

docs/tasks/kubectl/shell-demo.yaml

@@ -0,0 +1,14 @@
+apiVersion: v1
+kind: Pod
+metadata:
+  name: shell-demo
+spec:
+  volumes:
+  - name: shared-data
+    emptyDir: {}
+  containers:
+  - name: nginx
+    image: nginx
+    volumeMounts:
+    - name: shared-data
+      mountPath: /usr/share/nginx/html