DOC: Add line clarifying sorting using sort_values() (#60734)

fix docs

Author: Impaler343

pandas/core/frame.py

@@ -6890,7 +6890,8 @@ def sort_values(
             builtin :meth:`sorted` function, with the notable difference that
             this `key` function should be *vectorized*. It should expect a
             ``Series`` and return a Series with the same shape as the input.
-            It will be applied to each column in `by` independently.
+            It will be applied to each column in `by` independently. The values in the
+            returned Series will be used as the keys for sorting.
 
         Returns
         -------

pandas/core/generic.py

@@ -4884,7 +4884,8 @@ def sort_values(
             builtin :meth:`sorted` function, with the notable difference that
             this `key` function should be *vectorized*. It should expect a
             ``Series`` and return a Series with the same shape as the input.
-            It will be applied to each column in `by` independently.
+            It will be applied to each column in `by` independently. The values in the
+            returned Series will be used as the keys for sorting.
 
         Returns
         -------