No documented way to add a colorbar axis label

[maclariz]

Quite used to making plots with colorbars in matplotlib and having the colorbar and colorscale calibrated to the quantity being plotted and giving it a label of the quantity and units.

Recently discovered plotly for 3D cone plots which is a perfect representation of the 3D vector field I am plotting, and I have it all scaled to the absolute values of those vectors. Just one thing missing - a label with units for the colorbar to make it totally obvious that this is quantitative and the viewer can read of the quantities from the colors in a unit they understand. But cannot find any documentation anywhere or even a forum post explaining such an apparently simple thing.