While learning Godot, the tutorial dictates how to add an icon to a class.
You may add a comma and an optional path to an image to use as an icon. You will then find your new type in the Node or Resource creation dialog.
Added a 16×16 svg file to the resources named something.svg .
Created a script with a path to that icon.
Added a node of that kind.
I don’t see that icon? Not sure why.