Allow using icons from the system theme directly in documentation
Currently, if people want to refer to an icon on a header bar in some documentation, they have to copy the icon from the system icon theme into their module’s git, and ship it with their help files, and refer to it using <media its:translate="no" type="image" src="figures/open-menu-symbolic.svg"><span its:translate="yes">settings</span></media>
. That uses disk space unnecessarily, and means the icons can easily get out of date. It also means that they won’t match the user’s icon theme if they use a non-standard icon theme.
This is particularly relevant for the burger menu, which people can’t easily refer to in documentation at the moment. A workaround of saying “the menu button in the top-right corner of the window” has been developed, but it’s not as clear as using the icon.
It would be good if Yelp/Mallard provided some way of referencing a system theme icon (by name) in the markup, and then Yelp would load it at render time.