Update README

Signed-off-by: Carlos Agüero <[email protected]>

ros_gz_sim_demos/README.md

@@ -14,17 +14,12 @@ There's a convenient launch file, try for example:
 
 Publishes fluid pressure readings.
 
-    ros2 launch ros_gz_sim_demos air_pressure.launch.py
+    ros2 launch ros_gz_sim_demos air_pressure.launch
 
-This demo also shows the use of custom QoS parameters. The sensor data is
-published as as "best-effort", so trying to subscribe to "reliable" data won't
-work. See the difference between:
+You can subscribe to receive the data with:
 
-    ros2 topic echo /air_pressure --qos-reliability best_effort
+    ros2 topic echo /air_pressure
 
-And
-
-    ros2 topic echo /air_pressure --qos-reliability reliable
 
 ![](images/air_pressure_demo.png)