Add new translation strings for international portals on mdorg

mdorg/en/portals.json

@@ -18,6 +18,9 @@
         "themator_in_german": "Themator in German",
         "themator_in_hungarian": "Themator in Hungarian",
         "Austria": "Austria",
-        "hungarian_portals": "Hungarian Regional Portals"
+        "hungarian_portals": "Hungarian Regional Portals",
+        "portals_in_serbia": "Regional Portals in Serbia",
+        "portals_in_romania": "Regional Portals in Romania",
+        "portals_in_the_usa": "Regional Portals in the USA"
     }
 }