update docstring examples of `torch.testing.assert_close` (#60163)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/60163
Changes to the default error message in case of mismatching values need to be reflected in the examples given in the docstring. Normally this should be enforced by a [`doctest`](https://docs.python.org/3/library/doctest.html). mruberry do you know why we don't have such a check?
Test Plan: Imported from OSS
Reviewed By: ngimel
Differential Revision: D29556353
Pulled By: mruberry
fbshipit-source-id: 8dbc3f566f429618811b542a059d9abde9a6530b
