chore: add upgrade docs for 1.33

Signed-off-by: Reza Abbasalipour <[email protected]>

Author: rapour

docs/canonicalk8s/snap/reference/releases.md

@@ -11,6 +11,7 @@ and backwards-incompatible changes.
 :titlesonly:
 :maxdepth: 2
 /snap/reference/versions/1.32
+/snap/reference/upgrading.md
 ```
 
 

docs/canonicalk8s/snap/reference/upgrading.md

@@ -0,0 +1,39 @@
+# Upgrade notes
+
+## Upgrade Instructions
+
+### 1.32 -> 1.33
+Updating the {{product}} snap to version 1.33 is straightforward in most cases. 
+If you are not using dual stack networking, you can simply run:
+
+```bash
+sudo snap refresh k8s --channel=1.33/stable
+```
+All components, including Cilium, will be updated automatically.
+
+#### Additional Steps for Dual Stack Environments
+If your cluster is configured with dual stack networking (IPv4 and IPv6), 
+you’ll need to make a manual adjustment before refreshing. {{product}} 1.33 
+includes Cilium v1.17, which introduces a stricter requirement for dual stack: 
+Each node must report both IPv4 and IPv6 addresses to the API server. 
+If this is not satisfied, the Cilium agent pods will fail to start. 
+For each node in the cluster, perform the following steps:
+- Edit the kubelet configuration:
+```bash
+sudo nano /var/snap/k8s/common/args/kubelet
+```
+- Locate the --node-ip flag.
+- Add both the IPv4 and IPv6 addresses (comma-separated) from the same interface:
+```bash
+--node-ip=<IPv4>,<IPv6>
+```
+- Restart the `kubelet` service
+```bash
+sudo systemctl restart snap.k8s.kubelet.service
+```
+- Restart the Cilium daemonset:
+```bash
+sudo k8s kubectl rollout restart daemonset cilium -n kube-system
+```
+
+Now you can run the snap `refresh` command to perform the upgrade.