Update control.md (#360)

Corrected the parametric example since `scale` isn't exported any longer.

Author: yakir12

docs/src/control.md

@@ -132,7 +132,7 @@ x = sin.(2π*t)
 y = cos.(2π*t)
 A = hcat(x,y)
 
-itp = scale(interpolate(A, (BSpline(Cubic(Natural(OnGrid()))), NoInterp())), t, 1:2)
+itp = Interpolations.scale(interpolate(A, (BSpline(Cubic(Natural(OnGrid()))), NoInterp())), t, 1:2)
 
 tfine = 0:.01:1
 xs, ys = [itp(t,1) for t in tfine], [itp(t,2) for t in tfine]