fix comment typo
register and unregister do not belong in dispatcher
Add ability to set touch-action properties on document and shadow roots

- __PointerEventShim__.register({document | shadow-root})
- Automatic with Mutation Observers (if shadow created before element insertion)
- Document and shadow roots can be manually set:
    `__PointerEventShim__.setTouchActionOnRoot({document | shadow-root},
    touch-action-string)`

- And manually unset:
    `__PointerEventShim__.removeTouchActionOnRoot({document | shadow-root})`
fix shadow sample for new API