Once you have the first question for your topic, you can add other questions simply by creating additional question files in the level folder. If you want to add questions with higher difficulty, just add an other folder l{index} and put some questions inside. Example :

- database
    - t01
        - l1
            - easy.md
            - nice.md
        - l2
            - ok.md
            - feasible.md
        - l3
            - clever.md
        - l4
            - hard.md

Of course, that's the same idea for questions on other topics ...

📜 You don't need a question for all levels, and you can also add more levels. Just always use this l{index} format !