message: Point to the doctest documentation
diff: @@ -100,9 +100,8 @@ class CustomOutputChecker(doctest.OutputChecker):
  _MESSAGE = textwrap.dedent("""\n
  #############################################################
  - Check the doctest documentation
  - (https://docs.python.org/3/library/doctest.html) on how to
  - write testable docstrings.
  + Check the documentation
  + (https://docs.python.org/3/library/doctest.html) on how to write testable docstrings.
  #############################################################""")
  def output_difference(self, example, got, optionflags):
  