Move topic to Injecting Data section. (#3623)

* Move topic to Injecting Data section.

* Update include paths.

* Remove old file.

docs/tasks/inject-data-application/secret-pod.yaml

@@ -0,0 +1,17 @@
+apiVersion: v1
+kind: Pod
+metadata:
+  name: secret-test-pod
+spec:
+  containers:
+    - name: test-container
+      image: nginx
+      volumeMounts:
+          # name must match the volume name below
+          - name: secret-volume
+            mountPath: /etc/secret-volume
+  # The secret data is exposed to Containers in the Pod through a Volume.
+  volumes:
+    - name: secret-volume
+      secret:
+        secretName: test-secret