message: Adding description for 2.0 tf.math.acos
diff: op {
  graph_op_name: "Acos"
  summary: "Computes acos of x element-wise."
  + description: <<END
  +
  + Provided an input tensor, the `tf.math.acos` operation returns the inverse cosine of each element of the tensor. Therefore, we can state that if `y = tf.math.cos(x)` then, `x = tf.math.acos(y)`.
  + Input range is `(-1, 1)` and the output has a range of `(0, pi)`.
  +
  + For example:
  +
  + ```python
  + x = tf.constant([1.0, -0.5, 3.4, 0.2, 0.0, -2], dtype = tf.float32)
  + tf.math.acos(x) ==> [0, 2.0943952, nan, 1.3694384, 1.5707964, nan] dtype=float32)
  + ```
  +END
  }
  