docs: 更新 layer 相关示例细节

docs/layer/examples/iframe.md

@@ -67,9 +67,9 @@ layui.use(function(){
         shadeClose: true,
         maxmin: true, //开启最大化最小化按钮
         area: ['900px', '600px'],
-        content: 'https://cn.bing.com/'
+        content: 'https://dashi.aliyun.com/activity/aigc?userCode=ap0255is'
       });
     }
   })
 });
-</script>
+</script>