docs(demo): Updated demo steps for local run

Author: jruaux

README.adoc

@@ -44,13 +44,20 @@ Set the following environment variable with the token:
 export TMDB_TOKEN=<your API read-access token>
 ----
 
-Finally use Docker Compose to launch containers for Redis and the {project-title} demo app instance:
+Use Docker Compose to launch containers for Redis, Prometheus and Grafana:
 
 [source,console]
 ----
 docker compose up
 ----
 
+Finally, launch the demo app with this command:
+
+[source,console]
+----
+./gradlew bootRun
+----
+
 // tag::demoSteps[]
 
 You can access the demo at http://localhost:8080/[http://localhost:8080,window=demo].