Update User Guide and Admin links to point to new resources. (#3438)

* Update links to outdated user-guide and admin docs

* Add script for updating outdated links.

* Update regex to include init-containers file.

* Pull upstream, rewrite links in and to namespaces walkthrough.

docs/tutorials/connecting-apps/connecting-frontend-backend.md

@@ -26,7 +26,7 @@ frontend and backend are connected using a Kubernetes Service object.
 * {% include task-tutorial-prereqs.md %}
 
 * This tutorial uses
-  [Services with external load balancers](/docs/user-guide/load-balancer/), which
+  [Services with external load balancers](/docs/tasks/access-application-cluster/create-external-load-balancer/), which
   require a supported environment. If your environment does not
   support this, you can use a Service of type
   [NodePort](/docs/user-guide/services/#type-nodeport) instead.
@@ -132,7 +132,7 @@ service "frontend" created
 **Note**: The nginx configuration is baked into the
 [container image](/docs/tutorials/connecting-apps/frontend/Dockerfile).
 A better way to do this would be to use a
-[ConfigMap](/docs/user-guide/configmap/), so
+[ConfigMap](/docs/tasks/configure-pod-container/configmap/), so
 that you can change the configuration more easily.
 
 ### Interact with the frontend Service
@@ -179,8 +179,8 @@ The output shows the message generated by the backend:
 
 {% capture whatsnext %}
 
-* Learn more about [Services](/docs/user-guide/services/)
-* Learn more about [ConfigMaps](/docs/user-guide/configmap/)
+* Learn more about [Services](/docs/concepts/services-networking/service/)
+* Learn more about [ConfigMaps](/docs/tasks/configure-pod-container/configmap/)
 
 {% endcapture %}