Allow whiteboards to be embedded in the doc

It would be more powerful if we could embed the whiteboard in the document.

For example, it would be nice to be able to paste a URL to show a preview screen, or to put a screenshot of the current whiteboard.

It would also be nice to be able to tweak a whiteboard embedded in a doc from within the doc.

Example usage

A whiteboard embedded in a meeting minutes doc can be expected to be actively accessed by participants.

It would be easier to draw diagrams by hand when creating documents, and more documents would be created using clickup docs.