message: Update Keras 2D convolution docs
diff: @@ -526,7 +526,8 @@ class Conv2D(Conv):
  provide the keyword argument `input_shape`
  (tuple of integers, does not include the sample axis),
  e.g. `input_shape=(128, 128, 3)` for 128x128 RGB pictures
  - in `data_format="channels_last"`.
  + in `data_format="channels_last"`. You can use `None` when
  + a dimension has variable size.
  Examples:
  