(torch/elastic) add documentation clarifying that torchrun is a console script to torch.distributed.run (#73598)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/73598
resolves https://github.com/pytorch/pytorch/issues/73319
Simply clarifies that `torchrun` is a console script that invokes `python -m torch.distributed.run`.
Test Plan: N/A doc change only, letting github CI validate that the docs build correctly.
Reviewed By: sinannasir, d4l3k
Differential Revision: D34558538
fbshipit-source-id: 70332c7efc57164a15eda6621575a7c6f14120c8
(cherry picked from commit a349c048c788ece514658a0c94dc0c87c9644e71)
