update CHANGELOG

CHANGELOG.rst

@@ -7,14 +7,25 @@ Since last release:
 
 **Added:**
 
-* Added `CHANGELOG.rst` and `CONTRIBUTING.rst`
+* Added `CHANGELOG.rst`, `.gitignore`, `CONTRIBUTING.rst`, 
+  and unit tests for `openmcyclus.Depletion` class. Also
+  added files for better reproduction of comparison benchmar  (#18)
+* Add input parameters to `DepleteReactor` for the thermal 
+  power (instead of just using `power_cap`) and flux 
+  (required input for running OpenMC with new version) (#18)
 
 **Changed:**
 
+* Change OpenMC dependency to v0.14.0, which includes adding 
+  parameters for using `DepleteReactor` (#18)
+
 **Removed:**
 
+* Remove `check_existing_recipes` method in `DepleteReactor` (#18)
+
 **Fixed:**
 
+
 v 0.1.0
 =========
 Initial release