title: how to add SVG to CSidebarNavTitle
body: <p>I'm using CoreUI sidebar , and using CRenderFunction for items previewing ,
  I want to add SVG icon and dropdown for each nav item</p>
  <p>here's content to render :-</p>
  <pre><code>export default [
  {
      _name: 'CSidebarNav',
      _children: [
          {
              _name: 'CSidebarNavTitle',
              _children: [i18n.tc('orders')],
          },
          {
              _name: 'CSidebarNavItem',
              name: i18n.tc('create_order'),
              to: '/' + prefix + '/create-order',
              icon: '',
          },
          {
              _name: 'CSidebarNavItem',
              name: i18n.tc('POS'),
              to: '/' + prefix + '/pos',
              icon: '',
          },
          {
              _name: 'CSidebarNavItem',
              name: &quot;POS Report&quot;,
              to: '/' + prefix + '/pos/daily',
              icon: '',
          },
          {
              _name: 'CSidebarNavItem',
              name: i18n.tc('orders'),
              to: '/' + prefix + '/orders',
              icon: ''
          },
      ]
  }
  </code></pre>
  <p>]</p>