message: Some PATH typo : no `train_dir` in tutorial
  This file uses `train_dir`. But in code file, there is no `train_dir`  anymore, it should be replaced with `log_dir` `input_data_dir` and `checkpoint_file` respectively
diff: @@ -47,7 +47,7 @@ training folder and then unpack that data to return a dictionary of `DataSet`
  instances.
  ```python
  -data_sets = input_data.read_data_sets(FLAGS.train_dir, FLAGS.fake_data)
  +data_sets = input_data.read_data_sets(FLAGS.input_data_dir, FLAGS.fake_data)
  ```
  **NOTE**: The `fake_data` flag is used for unit-testing purposes and may be
  @@ -369,7 +369,7 @@ may be instantiated to write the events files, which
  contain both the graph itself and the values of the summaries.
  ```python
  -summary_writer = tf.summary.FileWriter(FLAGS.train_dir, sess.graph)
  +summary_writer = tf.summary.FileWriter(FLAGS.log_dir, sess.graph)
  ```
  Lastly, the events file will be updated with new summary values every time the
  @@ -403,7 +403,7 @@ method will periodically be called to write a checkpoint file to the training
  directory with the current values of all the trainable variables.
  ```python
  -saver.save(sess, FLAGS.train_dir, global_step=step)
  +saver.save(sess, checkpoint_file, global_step=step)
  ```
  At some later point in the future, training might be resumed by using the
  @@ -411,7 +411,7 @@ At some later point in the future, training might be resumed by using the
  method to reload the model parameters.
  ```python
  -saver.restore(sess, FLAGS.train_dir)
  +saver.restore(sess, checkpoint_file)
  ```
  ## Evaluate the Model
  