Update changelog

Author: frozzare

CHANGELOG.md

@@ -1,6 +1,6 @@
 # Papi Changelog
 
-## [3.0.4](https://github.com/wp-papi/papi/releases/tag/v3.0.4) - 2016-XX-XX
+## [3.0.4](https://github.com/wp-papi/papi/releases/tag/v3.0.4) - 2016-03-23
 
 * Fixed: Require for link property [#165](https://github.com/wp-papi/papi/issues/165).
 * Fixed: Check so file exists before calling `file_get_contents` when reading page type files.