Related to:
- https://review.opendev.org/#/c/723044/
- https://governance.openstack.org/tc/goals/selected/ussuri/project-ptl-and-contrib-docs.html

Change-Id: I80edcba7366e4c3b43b440222e6e2c811f55e442

Use https instead of http to ensure the safety

Change-Id: I0a6a941b6e899d1f9a13e615454befce70f05d54

Replace the https://bugs.launchpad.net/oslo with
https://bugs.launchpad.net/oslo.middleware

Change-Id: I792ceb5e248fb562133fa94d67698314351dd7e3

Replace URLs for workflow documentation to appropriate parts of the
OpenStack Project Infrastructure Manual.

Change-Id: Iaf8f913453df0d8139a661dc731bbcfcbb95cc36

Ensure each exported class has a docstring.

Add API to the sphinx docs.

Fix a few formatting issues so the rendered docs look OK.

Change-Id: Ieef7bae3783a084249169fe9b80ab17518eee15f