Is it possible to add a node to the chart as a parent (ex: add supervisor)

[cthacker-udel]

Instead of adding the node as the child, is it possible to add it as the parent of the currently selected node.

I mean "currently selected node", because I have this cta buttons that appear when hovering over a node, one of them being the "+" button. I want to present in the add node Modal component, the option to set the new node as the parent of the node upon which you pressed the "+" with, if that makes any sense.

I sent this as a question because I'm unsure if it's been answered before, or if that functionality already exists.

[cthacker-udel]

Also, side-note: It seems that the Remove Node link in the README appears to be pointing to an addNode functionality example, not a removeNode example.

1. Go to README
2. Click on Remove Node
3. View that the interactive button is Add Node to the Root, which does not have any correlation with removal. Also the button onClick uses chart.addNode

PPS: Please merge this #347, the issue referenced in the PR is currently causing quite a headache with my implementation, would help out a lot, thanks!