How to use a workflow to update the template of another document library?

I have a document library called 'Templates' which holds all the templates for my team, mostly word docs (*.docx). I would like to have the documents copied from here, once approved, to their designated document library under the forms directory so that it can be used as the template. I'd like this done via workflow if possible.

For example, I have another library called 'Processes'. If the process template changes in the templates library, and approved, I'd like this workflow to update the template in the 'Processes' library, to ensure the libraries in sync.

I know how to copy documents to another library using workflows, but how to you set it as the template?