Add .cfg (config files) highlighting

I would like to have highlighting for .cfg files added to this theme as currently everything is white:

![image](https://github.com/dracula/notepad-plus-plus/assets/81376423/66243c1b-6c80-4a97-9909-433347b024e1)


Default has more highlighting:

![image](https://github.com/dracula/notepad-plus-plus/assets/81376423/4dc52981-0720-4730-96d5-b4e6aaf1e85e)