Add a live toast example to the docs
@mdo: your call if we want this in 4.6.0. BTW I need more eyes because of the different class names. I also had to specify a delay of 2000 to match the main docs.
Refs #31330 (closed)
Preview: https://deploy-preview-32827--twbs-bootstrap.netlify.app/docs/4.5/components/toasts/#live