Add note about how Events are handled

After I already described it in the JavaDocs and the Changelog...

Author: AB-xdev

README.md

@@ -12,6 +12,10 @@ To get started it's recommended to have a look at the demo (notably at the [mini
 
 ![demo](assets/demo.png)
 
+> [!NOTE]
+> The API only supports sending instructions to the client.<br/>
+> Due to data integrity retrieving client-side data (that can be modified by users) is not supported.
+> * Event listeners can still be registered but this needs to be done manually.<br/>[An example is available in the demo](https://github.com/xdev-software/vaadin-maps-leaflet-flow/blob/5a008511935105ea977187112cd0053c7de33e19/vaadin-maps-leaflet-flow-demo/src/main/java/software/xdev/vaadin/maps/leaflet/flow/demo/ComplexDemo.java#L223).
 
 ## Installation
 [Installation guide of the latest release](https://github.com/xdev-software/vaadin-maps-leaflet-flow/releases/latest#Installation)