message: move doctests before args: section
diff: @@ -1867,6 +1867,13 @@ def rgb_to_grayscale(images, name=None):
  last dimension of the output is 1, containing the Grayscale value of the
  pixels.
  + ```python
  + >>> original = tf.constant([[[1.0], [2.0], [3.0]]])
  + >>> converted = tf.image.rgb_to_grayscale(original)
  + >>> print(converted.shape)
  + (1, 3, 3)
  + ```
  +
  Args:
  images: The RGB tensor to convert. The last dimension must have size 3 and
  should contain RGB values.
  @@ -1874,13 +1881,6 @@ def rgb_to_grayscale(images, name=None):
  Returns:
  The converted grayscale image(s).
  -
  - ```python
  - >>> original = tf.constant([[[1.0], [2.0], [3.0]]])
  - >>> converted = tf.image.rgb_to_grayscale(original)
  - >>> print(converted.shape)
  - (1, 3, 3)
  - ```
  """
  with ops.name_scope(name, 'rgb_to_grayscale', [images]) as name:
  images = ops.convert_to_tensor(images, name='images')
  @@ -1904,19 +1904,19 @@ def grayscale_to_rgb(images, name=None):
  last dimension of the output is 3, containing the RGB value of the pixels.
  The input images' last dimension must be size 1.
  - Args:
  - images: The Grayscale tensor to convert. The last dimension must be size 1.
  - name: A name for the operation (optional).
  -
  - Returns:
  - The converted grayscale image(s).
  -
  ```python
  >>> original = tf.constant([[[1.0, 2.0, 3.0]]])
  >>> converted = tf.image.grayscale_to_rgb(original)
  >>> print(converted.shape)
  (1, 1, 1)
  ```
  +
  + Args:
  + images: The Grayscale tensor to convert. The last dimension must be size 1.
  + name: A name for the operation (optional).
  +
  + Returns:
  + The converted grayscale image(s).
  """
  with ops.name_scope(name, 'grayscale_to_rgb', [images]) as name:
  images = _AssertGrayscaleImage(images)
  