Update README.md

Author: cybergalactic

README.md

@@ -24,7 +24,7 @@ The Python Vehicle Simulator is a supplement to the Matlab MSS (Marine Systems S
   
  Animated GIF:
  /src/python_vehicle_simulator/ 
-  3D_animation.gif - 3D animation file which can be opened in a web browser
+  3D_animation.gif - 3D animation file which can be opened in a web browser by right-clicking the file
   
 For more information about mathematical modeling of marine craft and methods for guidance, navigation and control, please consult: