add documentation about upgrading the recipe

README.md

@@ -43,3 +43,6 @@ You can run them as, for example:
 ```bash
 $ abra app cmd open-inventory.example.net app clear_cache
 ```
+
+## How to upgrade the recipe
+Have a look here: [UPGRADE.md](UPGRADE.md)

UPGRADE.md

@@ -0,0 +1,21 @@
+# open-inventory
+
+## How to upgrade the recipe _(after a new upstream open-inventory release)_
+
+
+1. Update  `open-inventory-recipe/compose.yml`
+   - Update the open-inventory docker image version
+     - in `compose.yml -> services -> app -> image`
+       - `image: codeberg.org/eotl/open-inventory:0.0.13` (example)
+       - (optional - if you are an open-inventory maintainer) to have the image pushed to codeberg, from the `open-inventory` repository, there is a specific Make command for that:
+         - `make VERSION=0.0.13 build-production-image-and-push`
+   - Bump up the open-inventory service version: 
+     - in the `labels` section:
+     - `        - "coop-cloud.${STACK_NAME}.version=1.0.13"` (example)
+2. Commit the changes
+   - `git add compose.yml && git commit -m "Upgrade to 0.0.13""`
+3. Create an annotated tag _(simple tags wouldn't work with `abra`)_
+   - `git tag -a v1.0.13 -m "commit message, example: upgrade to version v1.0.13"`
+5. Push the newly created tag
+   - `git push origin tag v1.0.13`
+- Done: now you can run `abra app upgrade inventory.example.net` and you will be offered to choose the new version.