Update CHANGELOG.md

Add section for release v1.1.1

[ci skip]

(cherry picked from commit 512eb0f9)

CHANGELOG.md

@@ -4,19 +4,26 @@
 ## Unreleased
 
 ### Added
-* Documentation of Docker images and their usage in the CI/CD pipeline.
 * DORiE now depends on [`yaml-cpp`](https://github.com/jbeder/yaml-cpp/), a
     library for reading YAML files. The version required is >=5.2.0.
 
 ### 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.
 * `Simulation` is renamed `RichardsSimulation` and moved to 
 	[richards_simulation.hh](dune/dorie/interface/richards_simulation.hh).
 * `RichardsSimulation` now has its own `RichardsSimulationTraits` derived from
     `BaseTraits`, which defines all its member types. `BaseTraits` now have
     reduced content and are intended to be shared between models/simulations.
+
+
+## 1.1.1 (2018-08-21)
+
+### 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.
 * The test system folder was renamed from `testing` to [`test`](test).
 
 ### Fixed