Fix? nested id for the link tag (#17)

[krerkkiat]

The nested id for the tag appears to be solved, but not sure if it affects other part or not.

What I did was setting a breakpoint at https://github.com/sphinx-doc/sphinx/blob/bfce4f54b0fc010b04f0d17ad8b9d47d8c279e1f/sphinx/domains/python/_object.py#L212 and with this

.. autoclass:: amod.AClass
    :members:

in the index.rst. When printing out classname it is None. (using the name, amod.AClass, from the comment in #17)

Since that is how autodoc do it, I set the py:class to None. With this change, the id appears to be normal and not nested.