CHANGELOG.md in problem_details-0.2.0 vs CHANGELOG.md in problem_details-0.2.1

@@ -1,4 +1,8 @@
+## 0.2.1 / 2018-03-31
+
+* Clarify supported ruby/gem versions
+
 ## 0.2.0 / 2018-03-20
 
 ### Enhancements:
 * Introduce a new gem, `sinatra-problem_details`, the Sinatra problem detail extention.