update README.md

README.md

@@ -4,7 +4,16 @@
 
 Environment variables are to be used for configuration. The most convenient way to set those variables is to copy [`.env_template`](.env_template) to `.env` and to edit it.
 
-## Deployment example
+## Using the Docker images
+
+Reusable Docker images are provided via GitLab's [container registry](https://git.rwth-aachen.de/dalia/backend/django/container_registry).
+
+### Maintained image tags
+
+* `latest`: built from the `main` branch; used in [DALIA's production system](https://search.dalia.education)
+* `dev`: build from the `dev` branch; used in DALIA's staging system
+
+### Deployment example
 
 [docker-compose.yml](docker-compose.yml) contains a simple example deployment of this Django application server and the [DALIA's Fuseki triplestore](https://git.rwth-aachen.de/dalia/backend/fuseki).
 
@@ -13,7 +22,7 @@ To start the deployment:
 docker-compose up
 ```
 
-To stop the deployed application:
+To stop and remove the deployed application:
 ```shell
 docker-compose down
 ```