fix function name

Author: ktseng4096

pandas/core/groupby/groupby.py

@@ -201,12 +201,12 @@ class providing the base-class of operations.
 
 See Also
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-Series.min : Return the min of the group values.
-DataFrame.min : Return the min of the group values.
-Series.max : Return the max of the group values.
-DataFrame.max : Return the max of the group values.
-Series.sum : Return the sum of the group values.
-DataFrame.sum : Return the sum of the group values.
+SeriesGroupBy.min : Return the min of the group values.
+DataFrameGroupBy.min : Return the min of the group values.
+SeriesGroupBy.max : Return the max of the group values.
+DataFrameGroupBy.max : Return the max of the group values.
+SeriesGroupBy.sum : Return the sum of the group values.
+DataFrameGroupBy.sum : Return the sum of the group values.
 
 Examples
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