Updated translation. (#1048)

translations/fr-fr.all.json

@@ -715,6 +715,10 @@
     "id": "email_address",
     "translation": "Adresse email"
   },
+  {
+    "id": "optional",
+    "translation": "Facultatif"
+  },
   {
     "id": "email_not_valid",
     "translation": "L'adresse email est invalide !"