Add more option to Choosing a Backend docs - Cloudflare+GitHub

Hi, I would like to add description how to make this work on Cloudflare Pages + GitHub. It is ok to add this?

The setup backend page, to me as complete DecapCMS and also SSG beginner, was kinda confusing, since I also didn't want to use Netlify. So making it more clear and showing another option would for sure be beneficial for others as well.

**Is your feature request related to a problem? Please describe.**

**Describe the solution you'd like**

I will create a section on https://decapcms.org/docs/choosing-a-backend/ with description and tips to setup on CloudflarePages and Github + optionally custom preview setup using GitHub Action for check to status convert https://gist.github.com/onnenon/1d54863c06471531dc09f62c3d8a8945.

**Describe alternatives you've considered**

**Additional context**