Add changelog entry for defaultLevel (#70)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3017f89..0b9bc10 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,6 @@
-## 0.11.4
+## 0.11.4-dev
 
+* Add top level `defaultLevel`.
 * Require Dart `>=2.0.0`.
 
 ## 0.11.3+2