docs: update navigation

Author: mrholek

src/docs/nav.tsx

@@ -237,6 +237,10 @@ const nav = [
         name: 'Sidebar',
         to: '/components/sidebar/',
       },
+      {
+        name: 'Spinner',
+        to: '/components/spinner/',
+      },
       {
         name: 'Table',
         to: '/components/table/',