STYLE: Fix formatting/punctuation errors.

ScalarImageKmeansClassifier examples fixes:

It should use non-contiguous labels for the output to be displayed
in the ITKSoftwareGuide, and correct method/argument names.

Change-Id: I17853b85a6aa0872bd699c7a6c2824f6f992cfaf
Merge topic '4.7-book-fixes'

f6026394 STYLE: Fix formatting/punctuation errors.