message: Fix list formatting
  Markdown needs a blank line before the list to render it correctly.
diff: @@ -528,6 +528,7 @@ class RunConfig(object):
  """Returns a new instance of `RunConfig` replacing specified properties.
  Only the properties in the following list are allowed to be replaced:
  +
  - `model_dir`.
  - `tf_random_seed`,
  - `save_summary_steps`,
  