How to add a new menu item under the additional section of jContent?

Question

How to add a new menu item under the additional section of jContent?

Answer

You need to add a route to the target jcontent:20.

Here is a working example once added to this file of the Pokedex exercise with Jahia 8.2.1.0: 

    registry.add('adminRoute', 'additionalPokedexDashboard', {
        targets: ['jcontent:20'],
        icon: <Cloud/>,
        label: 'pokedex:label.settings.title',
        isSelectable: true,
        render: () => React.createElement(App)
    });