CHANGELOG.md in flexirest-1.3.12 vs CHANGELOG.md in flexirest-1.3.13

@@ -1,6 +1,12 @@
 # Changelog
 
+## 1.3.13
+
+Feature:
+
+- The undocumented `plain: true` option to mapped methods was tested and documented.
+
 ## 1.3.12
 
 Bugfix:
 
 - The Travis build was breaking because Guard pulls in Listen, which only runs on Ruby 2.2 and above. So I removed Guard so the gem can be tested to work against older Ruby versions still.