CHANGELOG in prometheus_exporter-0.1.16 vs CHANGELOG in prometheus_exporter-0.2.0

@@ -1,4 +1,8 @@
+Unreleased
+
+- Follow Prometheus metric [naming conventions](https://prometheus.io/docs/practices/naming/#metric-names)
+
 0.1.15 - 2018-02-19
 
 - Feature: Prefer to use oj if it is loadable
 
 0.1.14 - 2018-02-17