See a list of nodes that have no incomming and no outgoing references

[BasilPH]

At the moment we only show Zettel with no connections at all. Based on the feedback from Will on https://forum.zettelkasten.de, it would be nice to see Zettel with no incoming or outgoing references as well.

It's not clear to me yet, if those should be separate commands or options for the unconnected command.