Fork/Join Inline Docs (relanding) (#40438)
Summary:
Added fork/wait to docs/source/jit.rst, hopefully that will fix test error.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/40438
Differential Revision: D22188152
Pulled By: eellison
fbshipit-source-id: c19277284455fb6e7c0138b0c1423d90b147d18e
