Improve error message for immutable desired state

If you try to change a property of the desired state (which is immutable), you will get the following JavaScript default message:
> Cannot assign to read only property 'arn' of object '#'

We should tell the developer to instantiate a new Resource Model, instead.

在仓库中搜索不可变 desired-state 的处理逻辑以及当前的 "Cannot assign to read only property" 消息，然后跟踪 ResourceModel 实例的创建方式。更新由此得到的错误指导，告知开发者实例化一个新的 Resource Model，并验证在尝试更改属性时会显示修订后的消息。

由索引模型根据 Issue 内容生成。