ob: adding noweb-ref to the list of header argument names

* lisp/ob.el (org-babel-header-arg-names): Adding noweb-ref to the
  list of header argument names.

lisp/ob.el

@@ -291,7 +291,8 @@ then run `org-babel-pop-to-session'."
 
 (defconst org-babel-header-arg-names
   '(cache cmdline colnames dir exports file noweb results
-    session tangle var eval noeval comments no-expand shebang padline)
+    session tangle var eval noeval comments no-expand shebang
+    padline noweb-ref)
   "Common header arguments used by org-babel.
 Note that individual languages may define their own language
 specific header arguments as well.")