add link for CakePHP 4 version

Author: rrd108

README.md

@@ -1,6 +1,8 @@
 # JsonApiException plugin for CakePHP
 
-Make your CakePHP 4 JSON REST API response more descriptive on errors.
+Make your CakePHP 5 JSON REST API response more descriptive on errors.
+
+For CakePHP 4 support use the [CakePHP 4 branch](https://github.com/rrd108/cakephp-json-api-exception)
 
 If you want a simple solution for token authentication for a CakePHP JSON REST API, then check this: [CakePHP API Token Authenticator](https://github.com/rrd108/api-token-authenticator)