Fix popover live demo to use `data-bs-title` instead of `title`

😅 Forgot to update one example in https://github.com/twbs/bootstrap/pull/36449. This live demo example must use data-bs-title instead of title for consistency with the other examples and the callout message, and for the title to be displayed in StackBlitz.

Before, if "Edit on StackBlitz" button is clicked, the title won't be displayed in StackBlitz after clicking on the "Click to toggle popover".

Live preview

/CC @GeoSot