message: Update merge.py
  fixed the typo
diff: @@ -757,7 +757,7 @@ def add(inputs, **kwargs):
  >>> print(y.shape)
  (2, 3, 4)
  - Used in a functiona model:
  + Used in a functional model:
  >>> input1 = tf.keras.layers.Input(shape=(16,))
  >>> x1 = tf.keras.layers.Dense(8, activation='relu')(input1)
  