add translation for add field

fix https://github.com/ohmyform/ui/issues/24

components/form/admin/fields.tab.tsx

@@ -74,7 +74,7 @@ export const FieldsTab: React.FC<Props> = (props) => {
                 props.onChangeFields(next)
               }}
             >
-              <PlusOutlined /> Add Field
+              <PlusOutlined /> {t('type:add')}
             </Button>
           </Space>
         </Form.Item>

locales/en/type.json

@@ -1,4 +1,5 @@
 {
+  "add": "Add Field",
   "confirmDelete": "Really remove this field? Check that it is not referenced anywhere!",
   "date": {
     "default": "Default Date",