Merge pull request #30961 from ystkfujii/v1.24_remove_section_on_dockershim

Set the dockershim state to deprecation.

Author: k8s-ci-robot

content/en/docs/concepts/containers/runtime-class.md

@@ -109,6 +109,11 @@ For more details on setting up CRI runtimes, see [CRI installation](/docs/setup/
 
 #### dockershim
 
+{{< feature-state for_k8s_version="v1.20" state="deprecated" >}}
+
+Dockershim is deprecated as of Kubernetes v1.20, and will be removed in v1.24. For more information on the deprecation,
+see [dockershim deprecation](/blog/2020/12/08/kubernetes-1-20-release-announcement/#dockershim-deprecation)
+
 RuntimeClasses with dockershim must set the runtime handler to `docker`. Dockershim does not support
 custom configurable runtime handlers.