message: Fix typo in video_input_psnr_ssim
diff: @@ -7,7 +7,7 @@ Goal
  Today it is common to have a digital video recording system at your disposal. Therefore, you will
  eventually come to the situation that you no longer process a batch of images, but video streams.
  These may be of two kinds: real-time image feed (in the case of a webcam) or prerecorded and hard
  -disk drive stored files. Luckily OpenCV threats these two in the same manner, with the same C++
  +disk drive stored files. Luckily OpenCV treats these two in the same manner, with the same C++
  class. So here's what you'll learn in this tutorial:
  - How to open and read video streams
  