chore: adding missing examples in the gallery for some chart types (#22766)

superset-frontend/plugins/plugin-chart-pivot-table/src/plugin/index.ts

@@ -28,6 +28,7 @@ import buildQuery from './buildQuery';
 import controlPanel from './controlPanel';
 import transformProps from './transformProps';
 import thumbnail from '../images/thumbnail.png';
+import example from '../images/example.jpg';
 import { PivotTableQueryFormData } from '../types';
 
 export default class PivotTableChartPlugin extends ChartPlugin<
@@ -51,6 +52,7 @@ export default class PivotTableChartPlugin extends ChartPlugin<
       description: t(
         'Used to summarize a set of data by grouping together multiple statistics along two axes. Examples: Sales numbers by region and month, tasks by status and assignee, active users by age and location. Not the most visually stunning visualization, but highly informative and versatile.',
       ),
+      exampleGallery: [{ url: example }],
       name: t('Pivot Table'),
       tags: [t('Additive'), t('Report'), t('Tabular'), t('Popular')],
       thumbnail,