added doc for using torch.distributed.launch/run

[oroojlooy]

Following up on #317, I created this PR.

[HuggingFaceDocBuilderDev]

The documentation is not available anymore as the PR was closed or merged.

[younesbelkada]

Thanks a lot for this!
For some reason the diff also shows that you have added the paragraph ### Run on multiple GPUs / node, but it seems that everything is correct as expected when looking at the generated documentation. Could you maybe merge your branch with trl's main branch?

cc @lvwerra

[oroojlooy]

Thanks a lot for this! For some reason the diff also shows that you have added the paragraph ### Run on multiple GPUs / node, but it seems that everything is correct as expected when looking at the generated documentation. Could you maybe merge your branch with trl's main branch?

cc @lvwerra

That was weird for me as well. I cloned the repo this morning to have a clean commit. Do you want me to re-do that with a new clone?

[younesbelkada]

I have updated your branch for you! Will merge once it is green