How to use <details> <summary> expandable content on GitHub with Markdown

Firstly, what is <details> <summary>?

The HTML Details Element (<details>) creates a disclosure widget in which information is visible only when the widget is toggled into an "open" state. A summary or label can be provided using the <summary> element. https://developer.mozilla.org/en-US/docs/Web/HTML/Element/details.

Example