Update CHANGELOG

CHANGELOG.md

@@ -178,4 +178,9 @@
   * Allows `PATCH` requests to primary endpoints that update autosaving collection relationships  to propagate the nested errors on attributes/relationships up to the primary data so error source pointers are just as detailed as they would be under `POST` requests already
   * Fields are now assigned in a specific order: attributes, singular relationships, collection relationships
 * Fix issue regarding `:base` field titles interpolated into error messages
-* Add more detailed error responses to `update_relationship_definition` endpoints
+* Add more detailed error responses to `update_relationship_definition` endpoints
+
+# Master
+
+* Switches to Rails 5, drops support for Rails 4
+* Protects against arrays being sent as data for create and update actions