#dm-docs-support -> #square-docs-support

[fajpunk]

Also, this build had rotted a bit, so I did some stuff to fix it:

• The types-pkg_resources package has been yanked from pypi. I replaced it with the types-setuptools package.
• The GitHub CI job needs AWS creds, it was using creds attached to Jonathan’s human IAM user. I made a new IAM user with access only to the lsst-the-docs-test S3 bucket.
• Changed the LTD_TEST_AWS_ID and LTD_TEST_BUCKET GitHub repo secrets into variables so that repo admins can see their values (LTD_TEST_AWS_SECRET remains a secret).
• Generated an access key for the new user and put the creds in the GitHub vars/secrets.
• Documented the GitHub CI / AWS integration.