Use set -x to help investigate doc push errors (#23111)
Summary:
I couldn't find any verbosity options in the [`docker pull` command docs](https://docs.docker.com/engine/reference/commandline/pull/), but
`docker pull` [got a `--quiet` option](https://github.com/docker/cli/pull/882) in a recent version (not sure if we're using that version), and `--quiet` for `docker push` [is forthcoming](https://github.com/docker/cli/pull/1221).
Pull Request resolved: https://github.com/pytorch/pytorch/pull/23111
Differential Revision: D16402993
Pulled By: kostmo
fbshipit-source-id: 52f77b11b839d28f8cf1ecb58518ca69632d7fbe
