SUMO extern controller options (cyberbotics#6259)

* SUMO extern controller

* Update docs/automobile/sumo-interface.md

Co-authored-by: Olivier Michel <Olivier.Michel@cyberbotics.com>

* Update projects/default/controllers/sumo_supervisor/sumo_supervisor.py

Co-authored-by: Olivier Michel <Olivier.Michel@cyberbotics.com>

---------

Co-authored-by: Olivier Michel <Olivier.Michel@cyberbotics.com>

Author: Benjamin Délèze

docs/automobile/sumo-interface.md

@@ -30,6 +30,11 @@ export WEBOTS_HOME=/snap/webots/current/usr/share/webots
 $WEBOTS_HOME/webots-controller $WEBOTS_HOME/projects/default/controllers/sumo_supervisor/sumo_supervisor.py
 ```
 
+If you want to set some SUMO options you have to specify them at the end of the launcher line, for example:
+```
+$WEBOTS_HOME/webots-controller $WEBOTS_HOME/projects/default/controllers/sumo_supervisor/sumo_supervisor.py --use-netconvert --no-gui
+```
+
 #### macOS
 
 Using [Homebrew](https://brew.sh), first install [XQuartz](https://www.xquartz.org) for the SUMO interface, that relies on X11, to work:

projects/default/controllers/sumo_supervisor/sumo_supervisor.py

@@ -31,6 +31,8 @@ def sumoImportError():
         if os.getenv('SNAP_NAME'):
             sys.stderr.write("Please set the 'SumoInterface.externController' field to TRUE and "
                              "launch the controller as extern controller.\n"
+                             "When launching the controller as extern, you must specify the SUMO options like --no-netconvert "
+                             "or --no-gui manually.\n"
                              "Install SUMO ")
         else:
             sys.stderr.write("Please install it ")