docs: update example to use file_path arg; reflecting updated BatchJo…

…b.create_from_messages (#1096)

docs/cli/batch.md

@@ -96,23 +96,20 @@ You'll need to supply a valid .jsonl file in order to be able to create a Batch
  messages = [
   [
   {
-  "role": "system",
+  "role": "user",
   "content": f"Classify the following email {email}",
   }
   ]
   for email in emails
  ]
 
- import json
-
- with open("output.jsonl", "w") as f:
-  for line in BatchJob.create_from_messages(
-  messages,
-  model="gpt-3.5-turbo",
-  response_model=Classification,
-  max_tokens=100,
-  ):
-  f.write(json.dumps(line) + "\n")
+ BatchJob.create_from_messages(
+  messages,
+  model="gpt-3.5-turbo",
+  response_model=Classification,
+  max_tokens=100,
+  file_path="output.jsonl"
+ )
  ```
 
 You can then import in the .jsonl file using the `instructor batch create-from-file` command