Headings are one of the most important elements of structure. When headings are properly used they create hierarchical data structures; which are leveraged by web browsers, screen reader software, and this particular documentation framework to organize headings. 

Design Guidelines

• Sections, such as 'Design Guidelines', should be stylized with an appropriate heading. 
• In this case 'Headings', 'Design Guidelines', and 'An Example' are formatted as a Heading 2, because the title of the page 'Headings' defaults to a Heading 1.

An Example

Below there are a number of formatted headings with a Table of Contents inserted into this document rendering headings to depict how the nest appropriately. 

Example Headings (Heading 3)

Heading 3

Heading 4

Heading 5

Heading 6

Heading 5

Example Table of Contents

More about Page Structures