Improve documentation about the PyPI set up and release process

The problem

Unless you're extremely familiar with them, the documentation of the PyPI set up and release process is very thin.

Definition of "done"

• improved the documentation about how to set up the trusted publisher. For example, what to put in the workflow file field (and the difference between the release and deploy steps in the CI)
• point to the documentation that is auto-generated and describes the release process from the set up docs
• improve the documentation about what the release process is actually doing (i.e. explain that it is auto-tagging, creating a new commit etc.)
• add a note that, if you're not the owner of your org, you will need your org owner to approve your token request
• add notes about protecting the main branch and protecting the deploy environment

Additional context