Fix typo in docstring

Author: gabrielmbmb

Diff for: src/distilabel/steps/tasks/magpie/base.py

@@ -219,7 +219,7 @@ class Magpie(Task, MagpieBase):
 
     Output columns:
         - conversation (`ChatType`): the generated conversation which is a list of chat
-            items with a role and a message. Only if `only_instructions=False`.
+            items with a role and a message. Only if `only_instruction=False`.
         - instruction (`str`): the generated instructions if `only_instruction=True`.
         - model_name (`str`): The model name used to generate the `conversation` or `instruction`.