Allow double width the first row i.e. the labels, add footnotes to the diagram

Hi @rdboyes,

This package does a great job. I would like to suggest allowing to control the width of the first row. For example, I have a long label for my intervention group and when I add "\n" the label gets cut. Would it be possible to allow double the space for the first row?

Also, I think allowing adding footnotes should be easy. Would that be possible?