Move "Object management using kubectl"

The section contains four articles which fit better under concepts.

Closes: #4178

docs/concepts/overview/object-management-kubectl/simple_deployment.yaml

@@ -0,0 +1,16 @@
+apiVersion: apps/v1beta1
+kind: Deployment
+metadata:
+  name: nginx-deployment
+spec:
+  minReadySeconds: 5
+  template:
+    metadata:
+      labels:
+        app: nginx
+    spec:
+      containers:
+      - name: nginx
+        image: nginx:1.7.9
+        ports:
+        - containerPort: 80