docs(modal/slideover): improve programmatic examples (#3131)

docs/app/components/content/examples/modal/ModalExample.vue

@@ -4,12 +4,21 @@ const modal = useModal()
 defineProps<{
   count: number
 }>()
+
+const emit = defineEmits(['success'])
+
+function onSuccess() {
+  emit('success')
+}
 </script>
 
 <template>
   <UModal :title="`This modal was opened programmatically ${count} times`">
     <template #footer>
-      <UButton color="neutral" label="Close" @click="modal.close()" />
+      <div class="flex gap-2">
+        <UButton color="neutral" label="Close" @click="modal.close()" />
+        <UButton label="Success" @click="onSuccess" />
+      </div>
     </template>
   </UModal>
 </template>