The Github files include a YML file with the theme settings inside it. The “Import theme” process presumably uses that YML file to make the setting fields appear. But, when I’m writing my own theme (not plugin), how do I create theme settings / parameters like this?
Looks like it can’t be done via the interface and requires the files to be placed on Github. Never posted on Github before, so will have to give it a try, to test myself.