Custom RTE plugin to create unordered list having checkmark



One of our project requirement is to add tick / checkmark symbol (✓) instead of bullets in unordered list? Looking for a solution as how this can be added.

I have overlay js file Iibs/clientlibs/granite/richtext/core/js/plugin/listplugin.js under apps folder to add 4th option in List section but not getting how to add  new css class to display list having checkmark sign.

All your help and suggestion would be really helpful. Also, please let me know if there is any other approach to implement this.