feat(SidebarNav): navLink attributes - optional JS object with valid JS API naming

- starting with `@coreui/coreui`, `@coreui/react` `v2.1.0` and up
- valid attributes: `rel`, `target`, `hidden`, `disabled`, etc...

src/_nav.js

@@ -255,18 +255,26 @@ export default {
         },
       ],
     },
+    {
+      name: 'Disabled',
+      url: '/dashboard',
+      icon: 'icon-ban',
+      attributes: { disabled: true },
+    },
     {
       name: 'Download CoreUI',
-      url: 'http://coreui.io/react/',
+      url: 'https://coreui.io/react/',
       icon: 'icon-cloud-download',
       class: 'mt-auto',
       variant: 'success',
+      attributes: { target: '_blank', rel: "noopener" },
     },
     {
       name: 'Try CoreUI PRO',
-      url: 'http://coreui.io/pro/react/',
+      url: 'https://coreui.io/pro/react/',
       icon: 'icon-layers',
       variant: 'danger',
+      attributes: { target: '_blank', rel: "noopener" },
     },
   ],
 };