Icons
The available icons depends on what icons you have installed. They will match the filename without extension, taken from both the svg and png folder.
A popular repository for getting these icons is at: https://github.com/walkxcode/Dashboard-Icons. You can also get my app icons at: https://github.com/enchant97/app-icons. These projects are both in the correct format.
Adding Icons
To set the icon name config you will need icons in the icon folder, these will need to be arranged in the format shown below:
icons/
svg/
some-app.svg
png/
some-app.png