Fix __config__ docs (#48557)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/48287
Pull Request resolved: https://github.com/pytorch/pytorch/pull/48557
Reviewed By: ngimel
Differential Revision: D25211872
Pulled By: mruberry
fbshipit-source-id: ac916e16722809e747bd8960675c1477e3a1084d
