message: fix changelog; add entry
diff: @@ -5,11 +5,12 @@ All PRs to the Wasmer repository must add to this file.
  Blocks of changes will separated by version increments.
  ## **[Unreleased]**
  +- [#399](https://github.com/wasmerio/wasmer/pull/399) Add example of using a plugin extended from WASI
  +- [#397](https://github.com/wasmerio/wasmer/pull/397) Fix WASI fs abstraction to work on Windows
  +- [#390](https://github.com/wasmerio/wasmer/pull/390) Pin released wapm version and add it as a git submodule
  ## 0.4.0 - 2018-04-23
  -- [#397](https://github.com/wasmerio/wasmer/pull/397) Fix WASI fs abstraction to work on Windows
  -- [#390](https://github.com/wasmerio/wasmer/pull/390) Pin released wapm version and add it as a git submodule
  - [#383](https://github.com/wasmerio/wasmer/pull/383) Hook up wasi exit code to wasmer cli.
  - [#382](https://github.com/wasmerio/wasmer/pull/382) Improve error message on `--backend` flag to only suggest currently enabled backends
  - [#381](https://github.com/wasmerio/wasmer/pull/381) Allow retrieving propagated user errors.
  