Progressive slides support like in lookatme using `<!-- stop -->`

Describe the solution you'd like

lookatme has this nice feature, where when we add a <!-- stop --> somewhere in the markdown file, what is right after the <!-- stop --> will not get render till the next key press.

Describe alternatives you've considered This can be achieved in slides by creating a duplicate of the same slides with incremental changes. But add some effort.

Additional context instead of showing all the points right away, with this I can reveal one point at a time. If we can add this as a feature, that will be pretty cool