Add Doxygen documentation

[Panquesito7]

It would be nice if you could add Doxygen documentation.
For reference, you can see the TheAlgorithms/C repository.

I can also help with this if required/needed (I'm very good with that stuff).
IMHO, this will make the code much more understandable, clean and better. 🙂

[StepfenShawn]

That's a good idea! But I have to tell you that the current situation of Square language is not stable, some features can not run well, so too much code needs to be modified.

I will spare more time to improve the features of square. My goal is to release version 1.0 before 2021. When Square releases version 1.0, you are welcome to contribute Doxygen documentation!😀