chore: add cascader entry into demo

example/config.js

@@ -45,6 +45,10 @@ export default [
         path: '/calendar',
         title: 'Calendar 日历',
       },
+      {
+        path: '/cascader',
+        title: 'Cascader 级联选择',
+      },
       {
         path: '/checkbox',
         title: 'Checkbox 复选框',