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* Update links to outdated user-guide and admin docs

* Add script for updating outdated links.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/concepts/overview/working-with-objects/labels.md

@@ -157,7 +157,7 @@ this selector (respectively in `json` or `yaml` format) is equivalent to `compon
 
 #### Resources that support set-based requirements
 
-Newer resources, such as [`Job`](/docs/concepts/jobs/run-to-completion-finite-workloads/), [`Deployment`](/docs/user-guide/deployments/), [`Replica Set`](/docs/user-guide/replicasets/), and [`Daemon Set`](/docs/admin/daemons/), support _set-based_ requirements as well.
+Newer resources, such as [`Job`](/docs/concepts/jobs/run-to-completion-finite-workloads/), [`Deployment`](/docs/concepts/workloads/controllers/deployment/), [`Replica Set`](/docs/concepts/workloads/controllers/replicaset/), and [`Daemon Set`](/docs/concepts/workloads/controllers/daemonset/), support _set-based_ requirements as well.
 
 ```yaml
 selector:

docs/concepts/overview/working-with-objects/namespaces.md

@@ -18,7 +18,7 @@ need the features they provide.
 
 Namespaces provide a scope for names.  Names of resources need to be unique within a namespace, but not across namespaces.
 
-Namespaces are a way to divide cluster resources between multiple uses (via [resource quota](/docs/admin/resourcequota/)).
+Namespaces are a way to divide cluster resources between multiple uses (via [resource quota](/docs/concepts/policy/resource-quotas/)).
 
 In future versions of Kubernetes, objects in the same namespace will have the same
 access control policies by default.