Publish Nuxeo Elements 3.0.x to webcomponents.org

We want to make our Nuxeo Elements library available on https://www.webcomponents.org/, to get some visibility and make it easier to get to the documentation and to the demos. In order to be able to publish there, we need to publish our packages to the public npm registry as well.

As we do this, we should also review our READM.ME file to take into account the recommendations on https://www.webcomponents.org/publish. I we should have our storybook published and linked there.