Update plots_digits_classification.py

DOC Update comment in plots_digits_classification

examples/classification/plot_digits_classification.py

@@ -25,7 +25,7 @@
 digits = datasets.load_digits()
 
 # The data that we are interested in is made of 8x8 images of digits, let's
-# have a look at the first 3 images, stored in the `images` attribute of the
+# have a look at the first 4 images, stored in the `images` attribute of the
 # dataset.  If we were working from image files, we could load them using
 # pylab.imread.  Note that each image must have the same size. For these
 # images, we know which digit they represent: it is given in the 'target' of