Update docs/tutorials/navigation.md

docs/tutorials/navigation.md

@@ -15,7 +15,7 @@ Then you can run some [navigation](http://wiki.ros.org/navigation) combination p
 
      You can save the generated map (yaml and pgm files) into the _iri_maps_ package (default) with:
 
-     ```roslaunch iri_rosnav save_map   ns:=helena  map_name:=my_map```
+     ```roslaunch iri_rosnav save_map.launch   ns:=helena  map_name:=my_map```
      
 
 * Navigation and [AMCL localization](http://wiki.ros.org/amcl), where the robot uses laser scan data to be localized in a map.