Fix small doc string typo

Author: shubh-agrawal

PathTracking/move_to_pose/move_to_pose.py

@@ -29,7 +29,7 @@ def move_to_pose(x_start, y_start, theta_start, x_goal, y_goal, theta_goal):
     beta is the angle between the robot's position and the goal position plus the goal angle
 
     Kp_rho*rho and Kp_alpha*alpha drive the robot along a line towards the goal
-    Kp*beta*beta rotates the line so that it is parallel to the goal angle
+    Kp_beta*beta rotates the line so that it is parallel to the goal angle
     """
     x = x_start
     y = y_start
@@ -126,4 +126,4 @@ def main():
 
 
 if __name__ == '__main__':
-    main()
+    main()