Update Graph docstring to match `__init__.py` (#48100)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/48100
Test Plan: Imported from OSS
Reviewed By: jamesr66a
Differential Revision: D25023407
Pulled By: ansley
fbshipit-source-id: e00706059b4c684451d2e1e48ca634b42693c1e1
