Add copyMakeBorder()

DIP2-cheatsheet.md

@@ -82,6 +82,7 @@ img.dtype
 ### Resize
 ```python
 cv2.resize(img, None, (0, 0), scale_x, scale_y, cv2.INTER_NEAREST)
+cv2.copyMakeBorder(img, top, bottom, left, right, cv2.BORDER_CONSTANT) #Pad with zeros. Top, bottom, etc. defines how many pixels get padded to each side
 ```
 
 ### Generate kernels