CI, DOC: Enable Sphinx parallel build
CI, DOC: Enable Sphinx parallel build

charris/numpy,seberg/numpy,jakirkham/numpy,simongibbons/numpy,numpy/numpy,mhvk/numpy,anntzer/numpy,endolith/numpy,anntzer/numpy,charris/numpy,seberg/numpy,mattip/numpy,seberg/numpy,mattip/numpy,seberg/numpy,mattip/numpy,charris/numpy,anntzer/numpy,pdebuyl/numpy,pdebuyl/numpy,jakirkham/numpy,mhvk/numpy,simongibbons/numpy,mattip/numpy,mhvk/numpy,rgommers/numpy,mhvk/numpy,jakirkham/numpy,charris/numpy,endolith/numpy,pdebuyl/numpy,endolith/numpy,simongibbons/numpy,pdebuyl/numpy,numpy/numpy,jakirkham/numpy,rgommers/numpy,simongibbons/numpy,anntzer/numpy,jakirkham/numpy,rgommers/numpy,simongibbons/numpy,endolith/numpy,numpy/numpy,numpy/numpy,mhvk/numpy,rgommers/numpy