CHANGELOG.md in logstash-output-mongodb-3.1.4 vs CHANGELOG.md in logstash-output-mongodb-3.1.5

@@ -1,4 +1,7 @@
+## 3.1.5
+  - Fixed @timestamp handling, BSON::ObjectId generation, close method [#57](https://github.com/logstash-plugins/logstash-output-mongodb/pull/57)
+
 ## 3.1.4
   - Docs: Set the default_codec doc attribute.
 
 ## 3.1.3
   - Update gemspec summary