code-block does not recognize emphasis-lines option

When using doc8 and validating RST files that have the emphasis-lines option per the docs at http://www.sphinx-doc.org/en/stable/markup/code.html this syntax is throwing a D000 error for 'code-block' directives:

.. code-block:: text
   :emphasize-lines: 2,3

   some text here
   some text here
   some text here
   some text here

Where this directive does not throw an error:

.. code-block:: text

   some text here
   some text here
   some text here
   some text here