use index in for vue code example

Example 1: v-for vue index

<ul id="example-2">
  <li v-for="(item, index) in items">
    {{ parentMessage }} - {{ index }} - {{ item.message }}
  </li>
</ul>

Example 2: vue for loop

<ul id="v-for-object" class="demo">
  <li v-for="value in object">
    {{ value }} 
  </li>
</ul>