docs: replace torch.distributed.run by torchrun

[panpan0000]

What does this PR do?

The old way will be deprecated , move to new torchrun.
FutureWarning: The module torch.distributed.launch is deprecated and will be removed in future. Use torchrun.

This PR only addresses the doc part, not touching the unit-test to limit the impact.

Fixes # (issue)

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[panpan0000]

I just found an old PR which did the similar work https://github.com/huggingface/transformers/pull/21780/files but out of sync.
but my PR just focus on DOC

[amyeroberts]

Thanks for adding this!

Just a few comments on removing the changes for the research examples.

For any future readers who stumble on this PR: the previously closed PR requested comments in the docs for older pytorch versions. We now officially support pytorch >= 1.10. The entrypoint torchrun is present from 1.10 onwards.

[panpan0000]

Thanks for adding this!

Just a few comments on removing the changes for the research examples.

For any future readers who stumble on this PR: the previously closed PR requested comments in the docs for older pytorch versions. We now officially support pytorch >= 1.10. The entrypoint torchrun is present from 1.10 onwards.

comments already addressed, now PR can be merged now.