Test repo for nested hugo shortcodes with Netlify-CMS

Netlify-CMS registerEditorComponent supports nested components in the fromBlock and the toBlock functions, but not in toPreview.

Refer to decaporg/decap-cms#1452 for more context.

To run:

1. In this repo, run npx netlify-cms-proxy-server in a terminal
2. Run hugo server in a different terminal
3. Navigate to http://localhost:1313/content-admin