[zh] kubeadm-init config file in beta

seems `alpha` outdated by mistake when docs were updated, so changed it to `beta`

https://kubernetes.io/docs/reference/setup-tools/kubeadm/kubeadm-init/#config-file

Author: qianjunakasumi

content/zh-cn/docs/reference/setup-tools/kubeadm/kubeadm-init.md

@@ -228,7 +228,7 @@ Alternatively, you can use the `skipPhases` field under `InitConfiguration`.
 <!--
 The config file is still considered beta and may change in future versions.
 -->
-配置文件的功能仍然处于 alpha 状态并且在将来的版本中可能会改变。
+配置文件的功能仍然处于 beta 状态并且在将来的版本中可能会改变。
 {{< /caution >}}
 
 <!--