The Learn theme for Hugo loads the Font Awesome library, allowing you to easily display any icon or logo available in the Font Awesome free collection.
Browse through the available icons in the Font Awesome Gallery. Notice that the free filter is enabled, as only the free icons are available by default.
Once on the Font Awesome page for a specific icon, for example the page for the heart, copy the HTML reference and paste into the markdown content.
The HTML to include the heart icon is:
<i class="fas fa-heart"></i>
<i> HTML into markup and Font Awesome will load the relevant icon.
Built with <i class="fas fa-heart"></i> from Grav and Hugo
Which appears as
Built with from Grav and Hugo
Font Awesome provides many ways to modify the icon
Check the full documentation on web fonts with CSS for more.