deprecate kubeadm alpha kubeconfig in 1.21

Author: carlory

content/en/docs/reference/setup-tools/kubeadm/_index.md

@@ -26,5 +26,7 @@ To install kubeadm, see the [installation guide](/docs/setup/production-environm
 * [kubeadm config](/docs/reference/setup-tools/kubeadm/kubeadm-config) if you initialized your cluster using kubeadm v1.7.x or lower, to configure your cluster for `kubeadm upgrade`
 * [kubeadm token](/docs/reference/setup-tools/kubeadm/kubeadm-token) to manage tokens for `kubeadm join`
 * [kubeadm reset](/docs/reference/setup-tools/kubeadm/kubeadm-reset) to revert any changes made to this host by `kubeadm init` or `kubeadm join`
+* [kubeadm certs](/docs/reference/setup-tools/kubeadm/kubeadm-certs) to manage Kubernetes certificates
+* [kubeadm kubeconfig](/docs/reference/setup-tools/kubeadm/kubeadm-kubeconfig) to manage kubeconfig files
 * [kubeadm version](/docs/reference/setup-tools/kubeadm/kubeadm-version) to print the kubeadm version
 * [kubeadm alpha](/docs/reference/setup-tools/kubeadm/kubeadm-alpha) to preview a set of features made available for gathering feedback from the community

content/en/docs/reference/setup-tools/kubeadm/generated/kubeadm_alpha_kubelet.md

@@ -4,8 +4,6 @@
 
 Kubeconfig file utilities.
 
-Alpha Disclaimer: this command is currently alpha.
-
 ### Options
 
    <table style="width: 100%; table-layout: fixed;">

content/en/docs/reference/setup-tools/kubeadm/generated/kubeadm_alpha_kubelet_config.md

@@ -4,17 +4,16 @@
 
 Output a kubeconfig file for an additional user.
 
-Alpha Disclaimer: this command is currently alpha.
 
 ```
-kubeadm alpha kubeconfig user [flags]
+kubeadm kubeconfig user [flags]
 ```
 
 ### Examples
 
 ```
   # Output a kubeconfig file for an additional user named foo using a kubeadm config file bar
-  kubeadm alpha kubeconfig user --client-name=foo --config=bar
+  kubeadm kubeconfig user --client-name=foo --config=bar
 ```
 
 ### Options