Update CHANGELOG.md

[ci skip]

CHANGELOG.md

@@ -3,10 +3,19 @@
 
 ## Unreleased
 
+### Added
+* Documentation of Docker images and their usage in the CI/CD pipeline.
+
+### Changed
+* Rebuilds of the DUNE environment Docker image are now triggered by setting the
+    CI variable `REBUILD_BASE_IMAGE` to a non-empty value. Previously, the
+    builds in stage `setup` where triggered by any manual pipeline run.
+
 ### Fixed
 * Removed VTK output from `dorie_mass_conservation` executable, which would
     cause the corresponding test to fail if the designated output directory did
     not exist.
+* Removed CI artifacts of `test` stage from `deploy` jobs.
 
 
 ## 1.1.0 (2018-07-27)

[Santiago Ospina De Los Ríos]

Isn't it were instead of where?

[Lukas Riedel]

Yeah ....