[1/n][torch/elastic] Move torchelastic docs *.rst (#148)
Summary:
Pull Request resolved: https://github.com/pytorch/elastic/pull/148
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56811
Moves docs sphinx `*.rst` files from the torchelastic repository to torch. Note: only moves the rst files the next step is to link it to the main pytorch `index.rst` and write new `examples.rst`
Reviewed By: H-Huang
Differential Revision: D27974751
fbshipit-source-id: 8ff9f242aa32e0326c37da3916ea0633aa068fc5
