wai-3.0.4.0: ChangeLog.md

## 3.0.4.0

* A new module Network.Wai.HTTP2 is exported.

## 3.0.3.0

* mapResponseHeaders, ifRequest and modifyResponse are exported.

## 3.0.2.3

* Allow blaze-builder 0.4

## 3.0.2.2

* Clarify some documentation on `rawPathInfo`. [Relevant Github
  discussion](https://github.com/yesodweb/wai/issues/325#issuecomment-69896780).