message: Update image_ops.py
diff: """Image ops.
  -The `tf.image` and the `tf.io` modules contain various functions for image
  -processing and decoding-encoding Ops respectively.
  +The `tf.image` module contains various functions for image
  +processing and decoding-encoding Ops.
  +
  +Many of the encoding/decoding functions are also available in the
  +core `tf.io` module.
  ## Image processing
  