Upgrade documentation 2022-06 -> 2022-09

[lfrancke]

Needs to be done by the time of the release
Copied from https://github.com/stackabletech/.github-private/blob/main/profile/README.md:

• Document how to use stackablectl to uninstall all and install new release
• Document how to use helm to uninstall all and install new release
• Every breaking change of all our operators
• List dropped supported product versions (if there are some)
• List dropped supported operators (if there are some)
• List supported k8s versions