Correct typos (AtsushiSakai#542)

* Update cubic_spline_planner.py

* Update rear_wheel_feedback.py

Author: Geonhee-LEE

PathPlanning/CubicSpline/cubic_spline_planner.py

@@ -195,7 +195,7 @@ def main():  # pragma: no cover
     import matplotlib.pyplot as plt
     x = [-2.5, 0.0, 2.5, 5.0, 7.5, 3.0, -1.0]
     y = [0.7, -6, 5, 6.5, 0.0, 5.0, -2.0]
-    ds = 0.1  # [m] distance of each intepolated points
+    ds = 0.1  # [m] distance of each interpolated points
 
     sp = Spline2D(x, y)
     s = np.arange(0, sp.s[-1], ds)

PathTracking/rear_wheel_feedback/rear_wheel_feedback.py

@@ -12,7 +12,7 @@
 from scipy import interpolate
 from scipy import optimize
 
-Kp = 1.0  # speed propotional gain
+Kp = 1.0  # speed proportional gain
 # steering control parameter
 KTH = 1.0
 KE = 0.5