fix bug

kubernetes/installation/containerd.md

@@ -11,7 +11,7 @@
 yum install -y yum-utils device-mapper-persistent-data lvm2 wget
 wget -O /etc/yum.repos.d/docker-ce.repo https://download.docker.com/linux/centos/docker-ce.repo
 sed -i 's+download.docker.com+mirrors.tuna.tsinghua.edu.cn/docker-ce+' /etc/yum.repos.d/docker-ce.repo
-yum makecache fast
+yum makecache
 yum install -y containerd.io
 ```