Potential move to @sphinx-doc

[AA-Turner]

Hi @ryan-roemer,

Would you consider moving this repo to https://github.com/sphinx-doc?

Projects such as https://github.com/pytest-dev/ & https://github.com/tox-dev/ have started to move to hosting extensions in the main organisation, and from a maintenence perspective it may be easier if the core Sphinx team are able to help!

Thanks,
Adam