Update Readme.md

Readme.md

@@ -18,6 +18,7 @@ To convert a .urdf description in its corresponding .mbs file :
 * Ensure that [template.mbs](mbs/template.mbs) is still present in the [mbs](mbs) folder
 * Open [gen.py](gen.py) and fill in the following lines at the end of the script :
     * `lower_limit` is the angle in radian under which a driven joint should not be taken into account
+    * 'joint_frames' is an option : set it to 1 if you want to see the joint frames in the visualization, 0 otherwise
 	* `path2wrl` is the path from the vrml folder to wrl files (in the Robotran project)
 	* `gravity` is a vector containing the x, y and z components of the gravity
 	* `urdf_file` is the file you want to convert (located in [urdf](urdf))