I am attempting to automate a [HUGO Static Site Generation system](https://gohugo.io/).

* Repo A is content that would normally be in the `/Content` directory.  

Repo A will be changed often and consists of just .md files.
* Repo B is a Hugo Site complete with a Theme directory.  

Repo B never changes often.
* Repo C is to be a combination of Repo A and B and compiled when there is a new push to Repo A (the content).

I suspect GitHub Action can do this on some sort of push event of repo A.

Where do I begin researching how this would be performed?  

Is there a better solution for maintaining the HUGO site and Hugo content in separate Repos?

FYI: This is a HUGO Project, which is a static site generator.