add back in reference to jit_unsupported section (#31486)
Summary:
It was added in https://github.com/pytorch/pytorch/pull/31329 and removed in a bad merge in https://github.com/pytorch/pytorch/pull/31138/
Pull Request resolved: https://github.com/pytorch/pytorch/pull/31486
Differential Revision: D19181967
Pulled By: eellison
fbshipit-source-id: 7e4b4a9b2042c30ec18f7f737bc4a9a56fac7d92
