DOC: Fix formatting in documentation (#32925)

Author: bartbroere

pandas/core/frame.py

@@ -6900,7 +6900,7 @@ def apply(self, func, axis=0, raw=False, result_type=None, args=(), **kwds):
         2    [1, 2]
         dtype: object
 
-        Passing result_type='expand' will expand list-like results
+        Passing ``result_type='expand'`` will expand list-like results
         to columns of a Dataframe
 
         >>> df.apply(lambda x: [1, 2], axis=1, result_type='expand')