Convert site to Hugo (#8316)

This commit converts content and layout to use Hugo.

content/en/docs/tasks/inject-data-application/envars.yaml

@@ -0,0 +1,15 @@
+apiVersion: v1
+kind: Pod
+metadata:
+  name: envar-demo
+  labels:
+    purpose: demonstrate-envars
+spec:
+  containers:
+  - name: envar-demo-container
+    image: gcr.io/google-samples/node-hello:1.0
+    env:
+    - name: DEMO_GREETING
+      value: "Hello from the environment"
+    - name: DEMO_FAREWELL
+      value: "Such a sweet sorrow"