DOC: Fix incorrect reST markups in What's new (#61492)

Author: koyuki7w

doc/source/whatsnew/v1.0.0.rst

@@ -1114,7 +1114,7 @@ Numeric
 - Bug in :class:`UInt64Index` precision loss while constructing from a list with values in the ``np.uint64`` range (:issue:`29526`)
 - Bug in :class:`NumericIndex` construction that caused indexing to fail when integers in the ``np.uint64`` range were used (:issue:`28023`)
 - Bug in :class:`NumericIndex` construction that caused :class:`UInt64Index` to be casted to :class:`Float64Index` when integers in the ``np.uint64`` range were used to index a :class:`DataFrame` (:issue:`28279`)
-- Bug in :meth:`Series.interpolate` when using method=`index` with an unsorted index, would previously return incorrect results. (:issue:`21037`)
+- Bug in :meth:`Series.interpolate` when using ``method='index'`` with an unsorted index, would previously return incorrect results. (:issue:`21037`)
 - Bug in :meth:`DataFrame.round` where a :class:`DataFrame` with a :class:`CategoricalIndex` of :class:`IntervalIndex` columns would incorrectly raise a ``TypeError`` (:issue:`30063`)
 - Bug in :meth:`Series.pct_change` and :meth:`DataFrame.pct_change` when there are duplicated indices (:issue:`30463`)
 - Bug in :class:`DataFrame` cumulative operations (e.g. cumsum, cummax) incorrect casting to object-dtype (:issue:`19296`)

doc/source/whatsnew/v2.2.0.rst

@@ -815,8 +815,8 @@ Conversion
 ^^^^^^^^^^
 - Bug in :meth:`DataFrame.astype` when called with ``str`` on unpickled array - the array might change in-place (:issue:`54654`)
 - Bug in :meth:`DataFrame.astype` where ``errors="ignore"`` had no effect for extension types (:issue:`54654`)
+- Bug in :meth:`DataFrame.loc` was not throwing "incompatible dtype warning" (see `PDEP6 <https://pandas.pydata.org/pdeps/0006-ban-upcasting.html>`_) when assigning a ``Series`` with a different dtype using a full column setter (e.g. ``df.loc[:, 'a'] = incompatible_value``) (:issue:`39584`)
 - Bug in :meth:`Series.convert_dtypes` not converting all NA column to ``null[pyarrow]`` (:issue:`55346`)
-- Bug in :meth:``DataFrame.loc`` was not throwing "incompatible dtype warning" (see `PDEP6 <https://pandas.pydata.org/pdeps/0006-ban-upcasting.html>`_) when assigning a ``Series`` with a different dtype using a full column setter (e.g. ``df.loc[:, 'a'] = incompatible_value``) (:issue:`39584`)
 
 Strings
 ^^^^^^^