Fix the cascading deletion page

This PR fixes two problems in the cascading deletion page:

- The indentation of list items should be 2 spaces for unordered lists,
  or 3 spaces for ordered lists. We should avoid using 4 spaces as
  indentation because 4-spaces indentation has special meaning in
  markdown.
- The garbage-collection page was moved to a new place. With redirect
  records for English site, there seems no obvious problems. However,
  for localization teams, such redirection records don't exist. It is
  super easy to create a dangling link in localized pages.

content/en/docs/tasks/administer-cluster/use-cascading-deletion.md

@@ -5,7 +5,8 @@ content_type: task
 
 <!--overview-->
 
-This page shows you how to specify the type of [cascading deletion](/docs/concepts/workloads/controllers/garbage-collection/#cascading-deletion)
+This page shows you how to specify the type of
+[cascading deletion](/docs/concepts/architecture/garbage-collection/#cascading-deletion)
 to use in your cluster during {{<glossary_tooltip text="garbage collection" term_id="garbage-collection">}}.
 
 ## {{% heading "prerequisites" %}}
@@ -26,7 +27,7 @@ kubectl get pods -l app=nginx --output=yaml
 
 The output has an `ownerReferences` field similar to this:
 
-```
+```yaml
 apiVersion: v1
     ...
     ownerReferences:
@@ -41,7 +42,7 @@ apiVersion: v1
 
 ## Use foreground cascading deletion {#use-foreground-cascading-deletion}
 
-By default, Kubernetes uses [background cascading deletion](/docs/concepts/workloads/controllers/garbage-collection/#background-deletion)
+By default, Kubernetes uses [background cascading deletion](/docs/concepts/architecture/garbage-collection/#background-deletion)
 to delete dependents of an object. You can switch to foreground cascading deletion
 using either `kubectl` or the Kubernetes API, depending on the Kubernetes
 version your cluster runs. {{<version-check>}}
@@ -349,4 +350,4 @@ kubectl get pods -l app=nginx
 
 * Learn about [owners and dependents](/docs/concepts/overview/working-with-objects/owners-dependents/) in Kubernetes.
 * Learn about Kubernetes [finalizers](/docs/concepts/overview/working-with-objects/finalizers/).
-* Learn about [garbage collection](/docs/concepts/workloads/controllers/garbage-collection/).
+* Learn about [garbage collection](/docs/concepts/architecture/garbage-collection/).