pie! should support labels kwarg

[NAThompson]

Feature description

Labeling pie! outputs is fairly challenging. None of the examples exhibit how to do it, and I struggled attempting the solutions presented in this discussion.

It would be preferable if pie! directly supported labels, or short of this, the Examples section exhibited a "blessed" workflow.

For plot types, please add an image of how it should look

This image presents a label in the sector, and a percentage:

This one puts the percentage in the sector, and the labels on the outside:

There are quite a few ways to do this-and honestly I'm not particularly picky about the end solution!