docs(readme): fix incorrect fileBatches.uploadAndPoll params (#1200)

Author: eric8he

README.md

@@ -133,7 +133,7 @@ const fileList = [
   ...
 ];
 
-const batch = await openai.vectorStores.fileBatches.uploadAndPoll(vectorStore.id, fileList);
+const batch = await openai.vectorStores.fileBatches.uploadAndPoll(vectorStore.id, {files: fileList});
 ```
 
 ### Streaming Helpers