Feature: automatically create docs for policy-server commands and flags

[viccuad]

OpenSSF best practices asks us to document our API. As cli tool, that means policy-server commands and flags.

Similar to kubewarden/kwctl#851.

Acceptance criteria

Add a new policy-server docs, that outputs a Markdown or similar file with the docs for all our clap commands and flags. This can be achieved with clap-markdown.

On release, and after building policy-server, run policy-server docs and ship the resulting markdown file as GH artifact in the GH release.

Use updatecli to consume the new markdown doc file from the GH release, and automate its inclusion into the reference section of kubewarden/docs.