Fix leading spaces in kubectl commands

This is causing bash/zsh shells to not to record the executed command in the
history. See this link for details: https://unix.stackexchange.com/questions/115917/why-is-bash-not-storing-commands-that-start-with-spaces

Signed-off-by: Ahmet Alp Balkan <ahmetb@google.com>

docs/tasks/access-kubernetes-api/http-proxy-access-api.md

@@ -13,7 +13,7 @@ This page shows how to use an HTTP proxy to access the Kubernetes API.
 * If you do not already have an application running in your cluster, start
   a Hello world application by entering this command:
 
-        kubectl run node-hello --image=gcr.io/google-samples/node-hello:1.0 --port=8080
+       kubectl run node-hello --image=gcr.io/google-samples/node-hello:1.0 --port=8080
 
 {% endcapture %}