[zh] Sync English site changes (9)

content/zh/docs/tasks/administer-cluster/kubeadm/kubeadm-certs.md

@@ -15,9 +15,9 @@ content_type: task
 {{< feature-state for_k8s_version="v1.15" state="stable" >}}
 
 <!-- 
-Client certificates generated by [kubeadm](/docs/reference/setup-tools/kubeadm/kubeadm/) expire after 1 year. This page explains how to manage certificate renewals with kubeadm. 
+Client certificates generated by [kubeadm](/docs/reference/setup-tools/kubeadm/) expire after 1 year. This page explains how to manage certificate renewals with kubeadm. 
 -->
-由 [kubeadm](/zh/docs/reference/setup-tools/kubeadm/kubeadm/) 生成的客户端证书在 1 年后到期。
+由 [kubeadm](/zh/docs/reference/setup-tools/kubeadm/) 生成的客户端证书在 1 年后到期。
 本页说明如何使用 kubeadm 管理证书续订。
 
 ## {{% heading "prerequisites" %}}
@@ -89,7 +89,7 @@ You can use the `check-expiration` subcommand to check certificate expiration.
 
 你可以使用 `check-expiration` 子命令来检查证书是否过期
 
-```
+```shell
 kubeadm alpha certs check-expiration
 ```