Check for two paths for each file
Check for two paths for each file

This is because HTMLDir can generate a file from two different places:

* foo.rst
* foo/index.rst

Both lead to `foo/index.html`

refs https://github.com/rtfd/readthedocs.org/issues/5368

rtfd/readthedocs.org,rtfd/readthedocs.org,rtfd/readthedocs.org,rtfd/readthedocs.org