add some comment

htdocs/opensurvey/class/opensurveysondage.class.php

@@ -44,6 +44,9 @@ class Opensurveysondage extends CommonObject
      */
     public $table_element='opensurvey_sondage';
 
+    /**
+     * @var string String with name of icon for myobject. Must be the part after the 'object_' into object_myobject.png
+     */
     public $picto = 'opensurvey';
 
     public $id_sondage;