pandas-dev#47030: update inplace docs

Author: Lily Fahey

pandas/core/frame.py

@@ -5155,8 +5155,7 @@ def rename(
         copy : bool, default True
             Also copy underlying data.
         inplace : bool, default False
-            Whether to return a new DataFrame. If True then value of copy is
-            ignored.
+            Whether to modify the DataFrame rather than creating a new one.
         level : int or level name, default None
             In case of a MultiIndex, only rename labels in the specified
             level.

pandas/core/generic.py

@@ -730,7 +730,7 @@ def set_axis(self, labels, axis: Axis = 0, inplace: bool_t = False):
             The axis to update. The value 0 identifies the rows%(axis_description_sub)s.
 
         inplace : bool, default False
-            Whether to return a new %(klass)s instance.
+            Whether to modify the %(klass)s instance rather than creating a new one.
 
         Returns
         -------