message: Fix description of `validation_data` in `fit`.
diff: @@ -959,13 +959,11 @@ class Model(base_layer.Layer, version_utils.ModelVersionSelector):
  noise and dropout.
  `validation_data` will override `validation_split`.
  `validation_data` could be:
  - - tuple `(x_val, y_val)` of Numpy arrays or tensors
  - - tuple `(x_val, y_val, val_sample_weights)` of Numpy arrays
  - - dataset
  - For the first two cases, `batch_size` must be provided.
  - For the last case, `validation_steps` could be provided.
  - Note that `validation_data` does not support all the data types that
  - are supported in `x`, eg, dict, generator or `keras.utils.Sequence`.
  + - A tuple `(x_val, y_val)` of Numpy arrays or tensors.
  + - A tuple `(x_val, y_val, val_sample_weights)` of NumPy arrays.
  + - A `tf.data.Dataset`.
  + - A Python generator or `keras.utils.Sequence` returning
  + `(inputs, targets)` or `(inputs, targets, sample_weights)`.
  shuffle: Boolean (whether to shuffle the training data
  before each epoch) or str (for 'batch'). This argument is ignored
  when `x` is a generator or an object of tf.data.Dataset.
  