Code comments about what example fold_virt_text_handler is doing

[technicalpickles]

Feature description

I am just starting out with ufo, and I’m having trouble understanding what exactly the example fold_virt_text_handler does, and how it is doing it. From the screenshot and the code, it looks like it’s adding virtual text with the number of lines in the fold?

Describe the solution you'd like

Some description of what the example customization is doing, and code comments about what some of the inputs / changes are.

Additional context

No response

[kevinhwang91]

Yes, feel free to update the docs :)

[technicalpickles]

That helps, thank you!