Correct the windows docs (#43479)
Summary:
Fixes https://discuss.pytorch.org/t/i-cannot-use-the-pytorch-that-was-built-successfully-from-source-dll-initialization-routine-failed-error-loading-caffe2-detectron-ops-gpu-dll/93243/5?u=peterjc123.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/43479
Reviewed By: mrshenli, ngimel
Differential Revision: D23294211
Pulled By: ezyang
fbshipit-source-id: d67df7d0355c2783153d780c94f959758b246d36
