CHANGELOG: Add Unreleased section back

Signed-off-by: John Andersen <[email protected]>

Author: John Andersen

CHANGELOG.md

@@ -4,6 +4,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+### Fixed
+- DataFlows with multiple possibilities for a source for an input, now correctly
+  look through all possible sources instead of just the first one.
+
 ## [0.3.0] - 2019-10-26
 ### Added
 - Real DataFlows, see operations tutorial and usage examples