Add new currencies Mark (GDR) and MDN (GDR)

src/MDCurrenciesSet.php

@@ -23,6 +23,8 @@ final class MDCurrenciesSet extends MDValueSet {
         'hu-Pengő',
         "pl-Złoty",
         "us-USD",
+        "ddr-Mark",
+        "ddr-MDN",
     ];
 
     /**