DOC: Only include numpy.std() note for std(), not all ddof (#42290)

Author: TheNeuralBit

pandas/core/generic.py

@@ -10499,6 +10499,7 @@ def mad(self, axis=None, skipna=None, level=None):
             name1=name1,
             name2=name2,
             axis_descr=axis_descr,
+            notes="",
         )
         def sem(
             self,
@@ -10520,6 +10521,7 @@ def sem(
             name1=name1,
             name2=name2,
             axis_descr=axis_descr,
+            notes="",
         )
         def var(
             self,
@@ -10542,6 +10544,7 @@ def var(
             name1=name1,
             name2=name2,
             axis_descr=axis_descr,
+            notes=_std_notes,
         )
         def std(
             self,
@@ -11034,12 +11037,16 @@ def _doc_params(cls):
 
 Returns
 -------
-{name1} or {name2} (if level specified)
+{name1} or {name2} (if level specified) \
+{notes}
+"""
+
+_std_notes = """
 
 Notes
 -----
 To have the same behaviour as `numpy.std`, use `ddof=0` (instead of the
-default `ddof=1`)\n"""
+default `ddof=1`)"""
 
 _bool_doc = """
 {desc}