Closure: Mention non-serializability of Closure objects (#5363)

* Mention non-serializability of Closure objects

Co-authored-by: Jordi Kroon <jordi@jordikroon.nl>

Author: mmalferov

language/predefined/closure.xml

@@ -76,6 +76,17 @@
    </informaltable>
   </section>
 
+  <section role="notes">
+   &reftitle.notes;
+   <note>
+    <simpara>
+     <classname>Closure</classname> objects cannot be serialized
+     as closures may contain bound variables and a specific execution context.
+     Attempting to serialize a closure will throw an <exceptionname>Exception</exceptionname>.
+    </simpara>
+   </note>
+  </section>
+
  </partintro>
 
  &language.predefined.closure.construct;