Update dcgan_faces_tutorial.py (#567)

Corrected to CHW not HWC (3x36x36)

Author: jspisak

beginner_source/dcgan_faces_tutorial.py

@@ -53,7 +53,7 @@
 # :math:`D(x)` is the discriminator network which outputs the (scalar)
 # probability that :math:`x` came from training data rather than the
 # generator. Here, since we are dealing with images the input to
-# :math:`D(x)` is an image of HWC size 3x64x64. Intuitively, :math:`D(x)`
+# :math:`D(x)` is an image of CHW size 3x64x64. Intuitively, :math:`D(x)`
 # should be HIGH when :math:`x` comes from training data and LOW when
 # :math:`x` comes from the generator. :math:`D(x)` can also be thought of
 # as a traditional binary classifier.