[TASK] Adding deprecated notice to register function

Classes/Service/MailTemplateService.php

@@ -195,6 +195,7 @@ class MailTemplateService {
 	 * description and subject can now be an array i.e. with elements such as 'en' => 'english description'
 	 * or an translation string used in locallang.xml
 	 *
+	 * @deprecated public usage of this function is deprecated. use registerByFile instead
 	 * @param string $extension
 	 * @param string $templateName
 	 * @param string $templatePath