doctest blocks are unknown

[ddeepwell]

Using doctests in the documentation breaks the docstrfmt linter.

When the linter runs on an rst file that includes

>>> import math
>>> math.sqrt(4)
2.0

the following error is printed: ValueError: Unknown node type doctest_block at File "/path/to/documentation.rst", line 6

It appears that the doctest extension is not handled.

[mayrholu]

Also code-blocks are not known.

Example:

.. code-block:: python

    >>> import module_xy
    >>> x = module_xy.function_xy(...)
    >>>

Causes: SyntaxError: invalid syntax:

[LilSpazJoekp]

I'll look into test blocks but code blocks that is intended and not meant to be used with >>>.