message: Update the docs to clear re-creation of evaluation graph.
  Fixes
diff: @@ -323,6 +323,10 @@ def train_and_evaluate(estimator, train_spec, eval_spec):
  tf.estimator.train_and_evaluate(estimator, train_spec, eval_spec)
  ```
  + Note that in current implementation `estimator.evaluate` will be called
  + multiple times. This means that evaluation graph (including eval_input_fn)
  + will be re-created for each `evaluate` call. `estimator.train` will be called
  + only once.
  Example of distributed training:
  