title: Child route component not rendering in vue js
body: <p>i have defined route like</p>
  
  <pre><code>{
          path:'/admins',
          name:'admin.admins',
          component: Admin,
          children: [
              {
                path:'add',
                name:'admin.add',
                component:addAdmin
              },
              {
                path:'edit/:id',
                name:'admin.edit',
                component:editAdmin
              }
          ]
      }
  </code></pre>
  
  <p>if i declare children route outside children like </p>
  
  <pre><code>{
          path:'/admins',
          name:'admin.admins',
          component: Admin
      },
      {
        path:'/add',
        name:'admin.add',
        component:addAdmin
      },
      {
        path:'/edit/:id',
        name:'admin.edit',
        component:editAdmin
      }
  </code></pre>
  
  <p>everything works fine but while visiting child routes, url in browser changes but component do not load. Only parent compenent shows up while visiting parent and child path.
  I am calling routes like</p>
  
  <pre><code>&lt;router-link :to="{ name:'admin.add' }"&gt;&lt;i class="fa fa-plus"&gt;&lt;/i&gt; Add Admin&lt;/router-link&gt;
  </code></pre>