Update to Docker example?

[Beanow]

We now have the docker images as a much easier way to use Soucrecred and the widgets.
Should we update the widget's /example to use them?

We also have #24 of doing this with GitHub actions as an option to move the example to, as well as the sourcecred/sourcecred#1232 (comment) planned renewed CLI + NPM package approach.

It seems like Docker over submodules would be a good improvement. But with all the new options coming. Should we have a new repo with multiple example setups instead? Or hold out a bit till we've converged on a preferred way?