Update repo information

In light of the move from apt.kubernetes.io to pkgs.k8s.io
(https://kubernetes.io/blog/2023/08/31/legacy-package-repository-deprecation/)
it makes sense to update this in the guide.

README.md

@@ -122,10 +122,10 @@ sudo apt-get install -y apt-transport-https ca-certificates curl
 
 **3. Configure apt-get cert and repo**
 ```bash
-sudo curl -fsSLo /etc/apt/keyrings/kubernetes-archive-keyring.gpg https://packages.cloud.google.com/apt/doc/apt-key.gpg
+curl -fsSL https://pkgs.k8s.io/core:/stable:/v$VERSION/deb/Release.key | sudo gpg --dearmor -o /usr/share/keyrings/kubernetes-apt-keyring.gpg
 ```
 ```bash
-echo "deb [signed-by=/etc/apt/keyrings/kubernetes-archive-keyring.gpg] https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list
+echo "deb [signed-by=/usr/share/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v$VERSION/deb/ /" | sudo tee /etc/apt/sources.list.d/kubernetes.list
 ```
 
 **4. Update apt and install `kubelet`, `kubeadm`, and `kubectl`**