CI/CLN: Fix linting in datetimes (pandas-dev#20351)

Author: TomAugspurger

pandas/core/indexes/datetimes.py

@@ -1790,7 +1790,7 @@ def freq(self, value):
         See Also
         --------
         quarter : Return the quarter of the date.
-        is_quarter_end : Similar property for indicating the start of a quarter.
+        is_quarter_end : Similar property for indicating the quarter start.
 
         Examples
         --------