Add docs for upgrading a live deployment

doc/LiveUpgrade.md

@@ -0,0 +1,17 @@
+# Upgrade major or minor versions of nextcloud
+
+## Nextcloud versions of c4k-nextcloud docker images
+
+- 4.0.3: nextcloud 22
+- 5.0.0: nextcloud 23
+- 6.0.0: nextcloud 24
+- 7.0.0: nextcloud 25
+
+## Uprgrading process
+
+1. Change the version of the docker image in the deployment to the next major version
+    - `kubectl edit deploy cloud-deployment`
+    - change `image: domaindrivenarchitecture/c4k-cloud:4.0.3`
+2. Wait for the pod to finish restarting
+3. Verify the website is working and https://URL/settings/admin/overview shows the correct version
+4. Repeat until desired version is reached