docs: fix vue example

examples/nuxt-example/components/ui/dropdown-menu/DropdownMenuSub.vue

@@ -0,0 +1,19 @@
+<script setup lang="ts">
+import {
+  DropdownMenuSub,
+  type DropdownMenuSubEmits,
+  type DropdownMenuSubProps,
+  useForwardPropsEmits,
+} from 'radix-vue'
+
+const props = defineProps<DropdownMenuSubProps>()
+const emits = defineEmits<DropdownMenuSubEmits>()
+
+const forwarded = useForwardPropsEmits(props, emits)
+</script>
+
+<template>
+  <DropdownMenuSub v-bind="forwarded">
+    <slot />
+  </DropdownMenuSub>
+</template>