Sidebar:

Code: Add the code below insrc/containers/Sidebar/Sidebar.js in between <Menu> Component. to add a new menu item in the sidebar.

// Add New Menu
<Menu.Item key="email">
  <Link to={`${url}/newmenu`}>
    <span className="isoMenuHolder">
      <i className="ion-android-mail" />
      <span className="nav-text">New Menu</span>
    </span>
  </Link>
</Menu.Item>

For Routing the menu now add the below code to the src/containers/App/AppRouter.js file. and add a New Component which will render when you click on the menu.

Code:

//menu routes
<Route
    exact
    path={`${url}/mailbox`}
    component={asyncComponent(() => import('path to NewMenuComponent'))}
/>