Remove `show-example` default

[TimeTravelPenguin]

Hi, I am working on the package Catppuccin and I am currently writing up the documentation, where I am using the theme that the library provides.

Currently, Tidy makes it very difficult to render examples that adhere to theming. For example, this line makes it impossible to set the preview theme, even if using the preamble argument in parse-module.

Could you please revise this function and remove any such defaults? I do not feel that explicitly setting the fill to white is necessary.

Thanks :)