Added info about how to check that everything runs correctly

README.md

@@ -39,6 +39,10 @@ Note that all the following commands reported here must be executed from the top
   ```
   (note: may add option `-d` to run in background, in which case logs are not displayed to standard output but are still accessible via `docker-compose logs`)
 
+* to test everything is running properly
+  - open the Ontop portal at `http://localhost:18080/` in a browser, click on tab `Example query` and run the query titled `All companies`, which should produce 3 results
+  - click on any URI under column `company`, which should open the LodView visualization of that individual in another browser tab, including title, description, properties and image
+
 * to stop the application, if running
   ```
   docker-compose down