Investigate options for Jekyll rendering of PR mods via GH Actions

[mwengren]

Investigate a way to render the site automatically when a pull request is generated to avoid image link path inconsistencies or other issues when markdown files are edited 'online' via GitHub rather than locally via text editor/local Jekyll environment.

For example, this theme flattens output structure so content in the images directory are stored alongside markdown files in the parent _docs directory when the site is rendered.

This makes link paths that appear correct via GitHub editor preview to actually fail in the rendered site, making online editing challenging.

Is there a way using GitHub Actions to render a preview of the site on PR submit so editors can verify if their changes are correct at that stage?

[mwengren]

Reference: ioos/ioos-metadata#24