Autogenerate documentation for new releases

**Describe the problem/challenge you have**
Right now the process to generate documentation for a new release is done manually following the steps in https://hackmd.io/uVpvITUuR4Cbwzkzb7MEpQ?view#Generate-new-docs-version
This process could be automatically triggered to create a new release when a new version is created.

**Describe the solution you'd like**
The idea would be similar to what we are doing with the update of the install script in the action https://github.com/vmware-tanzu/carvel-release-scripts/blob/main/.github/workflows/update-install-sh.yml

**Anything else you would like to add:**
Important things that we should take into account:
- When creating the docs it is important to know if this is a new version on top of the latest release version or a maintenance release since the script https://github.com/vmware-tanzu/carvel/blob/develop/site/hack/release-docs.sh needs that information to correctly produce the documentation
- This new automation needs to know the tool that is being released

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