Removed erroneous 's', reverted whatsnew to bugfix

Author: rhshadrach

doc/source/whatsnew/v1.1.0.rst

@@ -380,35 +380,6 @@ Assignment to multiple columns of a :class:`DataFrame` when some of the columns
    df[['a', 'c']] = 1
    df
 
-.. _whatsnew_110.api_breaking.as_index_false_with_std_and_sem:
-
-:meth:`DataFrameGroupby.std` and :meth:`DataFrameGroupby.sem` preserve group keys when ``as_index=False``
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-Using :meth:`DataFrameGroupby.std` and :meth:`DataFrameGroupby.sem` would previously alter the group keys when ``as_index=False``. Now, they are correctly left as the group keys. (:issue:`10355`)
-
-.. ipython:: python
-
-   df = pd.DataFrame({"a": [0, 0, 1, 1, 2, 2], "b": [1, 1, 2, 3, 5, 8]})
-   df
-
-*Previous behavior*:
-
-.. code-block:: ipython
-
-   In [3]: df.groupby("a", as_index=False).std()
-   Out[3]:
-          a         b
-   0  0.000000  0.000000
-   1  1.000000  0.707107
-   2  1.414214  2.121320
-
-*New behavior*:
-
-.. ipython:: python
-
-   df.groupby("a", as_index=False).std()
-
 .. _whatsnew_110.deprecations:
 
 Deprecations
@@ -632,6 +603,7 @@ Groupby/resample/rolling
 - Bug in :meth:`DataFrame.resample` where an ``AmbiguousTimeError`` would be raised when the resulting timezone aware :class:`DatetimeIndex` had a DST transition at midnight (:issue:`25758`)
 - Bug in :meth:`DataFrame.groupby` where a ``ValueError`` would be raised when grouping by a categorical column with read-only categories and ``sort=False`` (:issue:`33410`)
 - Bug in :meth:`GroupBy.first` and :meth:`GroupBy.last` where None is not preserved in object dtype (:issue:`32800`)
+- Bug in :meth:`DataFrameGroupby.std` and :meth:`DataFrameGroupby.sem` would modify grouped-by columns when ``as_index=False`` (:issue:`10355`)
 
 Reshaping
 ^^^^^^^^^

pandas/core/groupby/groupby.py

@@ -1271,7 +1271,7 @@ def std(self, ddof: int = 1):
             Degrees of freedom.
 
         Returns
-        -------s
+        -------
         Series or DataFrame
             Standard deviation of values within each group.
         """