Update to latest Mailu

README.md

@@ -25,11 +25,28 @@ host.
 4. `abra app config YOURAPPDOMAIN` - be sure to change `$WEB_DOMAIN` to something that resolves to
    your Docker swarm box
 5. `abra app deploy YOURAPPDOMAIN`
-9. Create initial user:
+6. Create initial user:
 ```
 abra app run YOURDOMAIN admin flask mailu admin admin YOURDOMAIN YOURPASSWORD
 ```
 
+## Upgrading the recipe
+
+**NOTE** This section is only intended for [recipe maintainers][maintainers]
+
+Minor/patch updates usually work OK with `abra recipe upgrade` and friends. 
+
+For major updates:
+
+1. Go to https://setup.mailu.io/ and generate a new config
+2. Download the new config and compare it to `compose.yml`. Pay attention to:
+  - New / removed services
+  - Added/removed config options
+  - Changes to networking
+3. Test upgrading from the previous version to the new version
+4. `abra recipe sync` / `abra recipe release` as normal
+
 [Mailu]: https://mailu.io/
 [abra]: https://git.autonomic.zone/autonomic-cooperative/abra
 [compose-traefik]: https://git.autonomic.zone/coop-cloud/traefik
+[maintainers]: https://docs.coopcloud.tech/maintainers/