Update README.md

Author: wkh237

README.md

@@ -494,9 +494,6 @@ When using DownloadManager, `fileCache` and `path` properties in `config` will n
 
 When download complete, DownloadManager will generate a file path so that you can deal with it.
 
-
-
-
 ```js
 RNFetchBlob
     .config({
@@ -517,6 +514,7 @@ RNFetchBlob
     })
 ```
 
+Your app might not have right to remove/change the file created by Download Manager, therefore you might need to [set custom location to the download task](https://github.com/wkh237/react-native-fetch-blob/issues/236).
 
 **Download Notification and Visibility in Download App (Android Only)**