From KDE UserBase Wiki

Insert a GUI icon image in the text. Usage: {{Icon|1=name-of-file}}.

The icon should be named Icon-name-of-file.png and preferably be uploaded in the size 22x22, since scaling down to this small size sometimes does not work well.

Note: Do not include the "Icon-" prefix or the ".png" suffix in the template.

Example: {{Icon|utilities-terminal}} yields . [[File:Icon-{{{1}}}.png|22px|link=]]