docs(modal): provide an example to bind event listeners (#1611)

docs/components/content/examples/ModalExampleComposable.vue

@@ -1,13 +1,20 @@
 <script setup lang="ts">
 import { ModalExampleComponent } from '#components'
 
+const toast = useToast()
 const modal = useModal()
 const count = ref(0)
 
 function openModal () {
   count.value += 1
   modal.open(ModalExampleComponent, {
-    count: count.value
+    count: count.value,
+    onSuccess () {
+      toast.add({
+        title: 'Success !',
+        id: 'modal-success'
+      })
+    }
   })
 }
 </script>