message: Formatting fix
  Formatting fix in documentation of `zeros_like` in backend.py.
diff: @@ -1679,10 +1679,10 @@ def zeros_like(x, dtype=None, name=None):
  Example:
  - from tensorflow.keras import backend as K
  - kvar = K.variable(np.random.random((2,3)))
  - kvar_zeros = K.zeros_like(kvar)
  - K.eval(kvar_zeros)
  + >>> from tensorflow.keras import backend as K
  + >>> kvar = K.variable(np.random.random((2,3)))
  + >>> kvar_zeros = K.zeros_like(kvar)
  + >>> K.eval(kvar_zeros)
  # array([[ 0., 0., 0.], [ 0., 0., 0.]], dtype=float32)
  