Some Shorthand plans offer additional publishing options including the ability to reference specific image file locations and to add custom HTML to the <HEAD> tag of a story. These actions take place when the story is processed for export or download.
If your plan includes these options, you'll find them in the settings panel accessed through the top-left of the story editor.
Asset URL (disabled by default):
If you add an asset URL, then in published stories (NOTE: Not preview) all relative links to assets (./), will be replaced with the link specified. For example:
Will change ./ to https://example.com/assets/