message: Updated maximum function with more detailed return and a simple example
diff: @@ -2245,7 +2245,19 @@ def maximum(x, y):
  y: Tensor or variable.
  Returns:
  - A tensor.
  + A tensor with the maximum value(s) of `x` and `y.
  +
  + Examples:
  + ```python
  + # maximum of two tensors
  + >>> x = tf.Variable([[1, 2], [3, 4]])
  + >>> y = tf.Variable([[2, 1], [0, -1]])
  + >>> m = tf.keras.backend.maximum(x, y)
  + >>> m
  + <tf.Tensor: id=42, shape=(2, 2), dtype=int32, numpy=
  + array([[2, 2],
  + [3, 4]], dtype=int32)>
  + ```
  """
  return math_ops.maximum(x, y)
  