[v4]: /utilities/image-replacement/ needs more documentation or examples

[ahmetb]

https://v4-alpha.getbootstrap.com/utilities/image-replacement/ is not helpful. It doesn't show how to "replace an element's content with a background image" as advertised.

[dillonchanis]

@Johann-S I could submit a PR for this. Providing an example and perhaps a description on why you would use it.

[Johann-S]

Sure @dillonchanis go ahead 👍