Fix missing attribute for NoDiscard

Author: kocsismate

language/predefined/attributes/nodiscard.xml

@@ -38,6 +38,7 @@
 
    <classsynopsis class="class">
     <ooclass>
+     <modifier role="attribute">#[\Attribute]</modifier>
      <modifier>final</modifier>
      <classname>NoDiscard</classname>
     </ooclass>