Remove virtual-scroller from examples

[dfabulich]

https://github.com/drufball/layered-apis/blob/master/README.md gives two examples of layered APIs: <virtual-scroller> and Async local storage.

The documentation also says:

• Does this feature need new low-level capabilities to work successfully? If so it, it isn't a good candidate yet; we need to fill in those gaps first.

But the <virtual-scroller> strategy now proposes to layer it on top of a new low-level capability (e.g. Display Locking, but Mozilla and Apple seem to be opposed to display locking, so perhaps a new alternative will emerge) that will allow find-in-page and a11y navigation to content without incurring the cost of layout.

I think <virtual-scroller> probably isn't a good example of a layered API at this time; maybe it will be a good example some day later when low-level capabilities are added.

For now, I don't think it makes sense to mention <virtual-scroller> as a good example of a layered API.