message: Adding mention of contrib optimizers and new learning rate decays.
diff: @@ -24,6 +24,8 @@ of the subclasses.
  * @{tf.train.ProximalAdagradOptimizer}
  * @{tf.train.RMSPropOptimizer}
  +See @{tf.contrib.opt} for more optimizers.
  +
  ## Gradient Computation
  TensorFlow provides functions to compute the derivatives for a given
  @@ -57,6 +59,9 @@ gradients.
  * @{tf.train.natural_exp_decay}
  * @{tf.train.piecewise_constant}
  * @{tf.train.polynomial_decay}
  +* @{tf.train.cosine_decay}
  +* @{tf.train.linear_cosine_decay}
  +* @{tf.train.noisy_linear_cosine_decay}
  ## Moving Averages
  