GitLab

* Simplify the requirements in the readthedoc yml

* Remove unused packages in the docs.txt

* Add m2r and recommonmark in the docs.txt

* Fix mistune version because the latest mistune does not have module BlockGrammar

* Add mmdet in the readthedocs.txt to compile api docs

* Add mmseg in the readthedocs.txt to compile api docs

* Fix the typo of mmseg (should be mmsegmentation)

* Add mmcv.ops into autodoc_mock_imports

* Add numba into readthedocs.txt to compile api docs

* Remove numba from readthedocs.txt and add runtime requirements in readthedocs.yml