Add asterisks to numbers instead of circles/squares/ellipses

[d-klug]

I really like the feature of ggcorrplot2 to be able to define confidence levels and mark correlations with asterisks. Based on the documentation, I was only able to make them appear for shapes (circles/squares/ellipses), but not next to numbers. I would actually prefer the other way around: show asterisks next to the numbers (maybe even allow significant correlation numbers to be bold) and don't show them on the shapes.
Is there currently a way to achieve this? Or could it be implemented? Thanks again for the great package you created!