update documentation

src/grasping/grasp_util.h

@@ -41,7 +41,7 @@ public:
      * Compute the "pre-pick"-pose
      * @param object_to_pick_pose pose of the object to pick (currently only vertically oriented objects are supported)
      * @param dimensions of the object
-     * @param orientation_gripper current gripper orientation
+     * @param orientation_gripper current gripper orientation relative to the link it is attached to
      * @param height specifies how much the pose is above the object
      * @return the "pre-pick"-pose
      */