feat: added portals demo to the online examples section

README.md

@@ -378,7 +378,7 @@ Contains the chart component that creates Highcharts chart.
 * Optimal way to update: [https://stackblitz.com/edit/highcharts-angular-optimal-way-to-update](https://stackblitz.com/edit/highcharts-angular-optimal-way-to-update)
 * Data from the service: [https://stackblitz.com/edit/highcharts-angular-data-from-service-2](https://stackblitz.com/edit/highcharts-angular-data-from-service-2)
 * Applying a custom plugin/wrap: [https://stackblitz.com/edit/highcharts-angular-custom-plugin](https://stackblitz.com/edit/highcharts-angular-custom-plugin)
-
+* Using portals to render an angular component within a chart: [https://stackblitz.com/edit/highcharts-angular-portal-usage](https://stackblitz.com/edit/highcharts-angular-portal-usage)
 
 ## Changing the Component
 
@@ -429,4 +429,8 @@ The correct repository to report such issues is [main Highcharts repository](htt
 #### Synchronized Charts Angular demo
 
 Based on original Highcharts demo for [Synchronized charts](https://www.highcharts.com/demo/synchronized-charts).
-Additionally added class based sync between charts - [demo](https://codesandbox.io/s/5wwz8qy1l4).
+Additionally, added class based sync between charts - [demo](https://codesandbox.io/s/5wwz8qy1l4).
+
+#### I want to render angular component in the tooltip/axis formatter
+
+To render angular component within the chart you can use the angular [portals](https://material.angular.io/cdk/portal/overview) - [demo](https://stackblitz.com/edit/highcharts-angular-portal-usage)