document how to passthrough metainfo by frameworks / 补充框架如何使用 metainfo 进行信息透传的文档

[PureWhiteWu]

Currently there's no document about how to use this to passthrough information by frameworks, and we need to document it clearly.

现在没有关于框架如何使用这个库进行信息透传的详细文档，我们应当补充一个。