message: remove unnecessary imports in knn tutorials
diff: @@ -21,7 +21,6 @@ train_data, and next 250 samples as test_data. So let's prepare them first.
  @code{.py}
  import numpy as np
  import cv2 as cv
  -from matplotlib import pyplot as plt
  img = cv.imread('digits.png')
  gray = cv.cvtColor(img,cv.COLOR_BGR2GRAY)
  @@ -89,7 +88,6 @@ alphabets directly.
  @code{.py}
  import cv2 as cv
  import numpy as np
  -import matplotlib.pyplot as plt
  # Load the data, converters convert the letter to a number
  data= np.loadtxt('letter-recognition.data', dtype= 'float32', delimiter = ',',
  