Would love to see a post-render equivalent documented

Not that Nomad-Pack needs to be like Helm, but for work I came across a use-case, namely how can I take a community Helm Chart and make changes to it without forking / committing to the repo, and was left wondering "how would I do that with Nomad-Pack"?

It looks like there would be a way to perhaps do a `render` and then run a script against that output. Or perhaps some hcl-to-json converstion before processing. Either way, it would be cool to see some docs walking through how one would alter or add to an existing community pack.

Thanks,
Sam

Start by reviewing Nomad-Pack's existing documentation and the render workflow mentioned in the issue. Compare the possible post-render script and HCL-to-JSON approaches, then document a practical walkthrough for modifying or extending an existing community pack without forking it. Done means the workflow and its limitations are clear to users.

Written by the indexing model from the issue text.