update extended summary

Author: DaanVanHauwermeiren

pandas/core/series.py

@@ -2748,7 +2748,7 @@ def isin(self, values):
         Check whether ``values`` are contained in Series.
 
         Return a boolean Series showing whether each element in the Series
-        is exactly contained in the passed sequence of ``values``.
+        matches an element in the passed sequence of ``values`` exactly.
 
         Parameters
         ----------