Update empty and empty_like examples in docs (#68874)
Summary:
For some reason, the example for `torch.empty` showed the usage of `torch.empty_like` and the other way around. These are now swapped.
Fixes https://github.com/pytorch/pytorch/issues/68799
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68874
Reviewed By: wenleix
Differential Revision: D32646645
Pulled By: ejguan
fbshipit-source-id: c8298bcaca450aaa4abeef2239af2b14cadc05b3
