message: Update CHANGELOG.md for 1.4.0-beta2
diff: ## 1.14.0 _(Not Yet Released)_
  +#### Debugger
  +
  +* Fixes symbol loading while debugging apps running under .NET Core 2.1 (ex: netcoreapp 2.1) on Linux and macOS
  +* Fixes debug console message encoding issue on Windows ([#1775](https://github.com/OmniSharp/omnisharp-vscode/issues/1775)).
  +* Adds preliminary support for Linux ARM debugging
  +
  #### Editor
  * Fix to allow signature help return results for attribute constructors. ([#1814](https://github.com/OmniSharp/omnisharp-vscode/issues/1814), PR: [omnisharp-roslyn#1007](https://github.com/OmniSharp/omnisharp-roslyn/pull/1007))
  