Update kubeadm-upgrade.md

Author: rotimislaw

content/en/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade.md

@@ -101,6 +101,8 @@ sudo apt update
 sudo apt-cache madison kubeadm
 ```
 
+If you don't see the version you expect to upgrade to, [verify which kubernetes package repositories are used](https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/change-package-repository/#verifying-if-the-kubernetes-package-repositories-are-used)
+
 {{% /tab %}}
 {{% tab name="CentOS, RHEL or Fedora" %}}
 
@@ -337,4 +339,4 @@ these backup files will need to be cleared manually.
 `kubeadm upgrade node` does the following on worker nodes:
 
 - Fetches the kubeadm `ClusterConfiguration` from the cluster.
-- Upgrades the kubelet configuration for this node.
+- Upgrades the kubelet configuration for this node.