message: update demo template
diff: -import <%= packageLabel %>ChartPlugin from '@superset-ui/legacy-plugin-chart-<%= packageName %>';
  +import <%= packageLabel %>ChartPlugin from '../../../../superset-ui-legacy-plugin-chart-<%= packageName %>';
  import Stories from './Stories';
  new <%= packageLabel %>ChartPlugin().configure({ key: '<%= packageName %>' }).register();
  