Fix 'Falling Lines' frozen line on start

[wkd-kapsule]

Hey!

The Falling Lines animation has a frozen line on first load that suddenly disappears.
To see it in action, just visit the docs.

After copying/pasting the source code, I've managed to trace the origin: the second and third <rect /> have an opacity animation going from 0 to 1 to 0. But the begin prop used to mark a delay also delays the initial setting of opacity to 0.

I have fixed it by simply adding an opacity={0} prop to both <rect /> to enforce their initial state.

If I knew how to contribute to this project I'd do it myself, so can someone add this to the source code for future usage?

Thanks! And nice project by the way, it is very convenient.