Upload: fix migrating message typo (#3510)

packages/upload/src/index.vue

@@ -188,7 +188,7 @@ export default {
       return {
         props: {
           'default-file-list': 'default-file-list is renamed to file-list.',
-          'show-upload-list': 'show-file-list is renamed to show-file-list.',
+          'show-upload-list': 'show-upload-list is renamed to show-file-list.',
           'thumbnail-mode': 'thumbnail-mode has been deprecated, you can implement the same effect according to this case: http://element.eleme.io/#/zh-CN/component/upload#yong-hu-tou-xiang-shang-chuan'
         }
       };