Automate pre-release documentation updates

[slinkydeveloper]

We now have a few manual steps to update the documentation before release, such as the following https://github.com/restatedev/documentation#releasing-the-documentation plus in future we'll most likely have tsdocs and javadocs released with it. We should automate the release process, by having a workflow that automatically generates these files and creates a pull request with them.

[slinkydeveloper]

Done with #164