Wish: possibility to influence sankey label alignment vs nodes

Thanks for providing networkD3!

I have been playing with displaing a sankey diagram of voter migration (similar to here). `sankeyNetwork`
defaults to displaying the node labels inside, i.e. on top of the visualization. For this application, I would strongly prefer to have the labels in the margins, and I have not found a way to achieve that.

Did I overlook something? If not, here is my wish: it would be great if users could influence the position of the label relative to its node (e.g. similar to the `pos` argument in the base R text command).

Best regards,
Ulrike