docs: demonstrate the multiple useState with same key (#5059)

* Better demonstrate the UseState concept

Add another counter instance with the same id and show that they change in parallel

* Apply suggestions from code review

Co-authored-by: pooya parsa <pyapar@gmail.com>

examples/composables/use-state/app.vue

@@ -1,10 +1,12 @@
 <script setup>
 const counter = useState('counter', () => Math.round(Math.random() * 1000))
+const sameCounter = useState('counter');
 </script>
 
 <template>
   <NuxtExampleLayout example="composables/use-state">
     <div>Counter: {{ counter }}</div>
+    <div>Same Counter: {{ sameCounter }}</div>
     <div>
       <NButton class="font-mono" @click="counter++">
         +