upgrade (skupperproject#278)

Author: pwright

input/index.html.in

@@ -22,7 +22,7 @@ title: Documentation
 <h2 id="installation">Installation</h2>
 <p>Learn about installing the Skupper CLI and the controller.</p>
 <ul>
-  <li><a href="install/index.html">Installation</a></li>
+  <li><a href="install/index.html">Installation and upgrade</a></li>
 </ul>
 
 <h2 id="using-the-skupper-cli-on-kubernetes">Using the Skupper CLI on Kubernetes</h2>

input/install/index.md

@@ -106,3 +106,64 @@ On local systems, you can install the controller using:
 ```bash
 skupper system install -p  [podman, docker, linux]
 ```
+
+## Upgrading sites
+
+To upgrade a site, you need to upgrade the controller using the same method you used to install Skupper, for example, one of the following:
+
+* Applying the latest Helm chart
+* Applying the latest YAML
+
+To update the Skupper CLI:
+
+```bash
+curl https://skupper.io/v2/install.sh | sh
+```
+
+
+### Upgrading local sites
+
+There are two distinct procedures for updating your Skupper installation: updating the site configuration and manually updating the controller.
+
+**Standard Site Update** 
+
+To update an existing site to the latest images or configuration matching your current CLI version:
+
+**Procedure**
+
+1. Ensure you have the latest version of the Skupper CLI installed.
+2. Run the reload command:
+	```shell
+	skupper system reload
+	```
+	*This command refreshes the site definition and pulls the latest images associated with the CLI version.*
+
+**Updating the controller** 
+
+Currently, `skupper system uninstall` protects active sites by refusing to run if a site is detected. However, if you need to force an update to the **controller** itself (to pick up a new controller version) without deleting your sites, follow this manual workaround:
+
+**Prerequisites** 
+
+* Ensure your CLI is updated to the target version.
+
+**Procedure**
+
+1. Stop and remove the controller container. The container is named `<user>-skupper-controller`.
+	
+    **Podman**
+    ```
+	podman rm -f <user>-skupper-controller
+	```
+    **Docker**
+    ```
+	docker rm -f <user>-skupper-controller
+	```
+	*Note: Replace `<user>` with the specific username under which Skupper is running.*
+
+2. Re-install the controller.
+    Run the install command to recreate the controller using the new CLI version.
+	```
+	skupper system install
+	```
+
+3. Verify the controller is recreated with the updated version.