Collapsible Outline Example

• The first heading.
  • The first entry under the first heading.
    • An entry with no children.
    • An entry with no children.
    • An entry with no children.
• The second heading.
  • The first entry under the second heading.
    • An entry with no children.
    • An entry with no children.
    • An entry with no children.

From the article how do I create a collapsible outline?