DOC: fix RT03 for pandas.Index.to_numpy and pandas.Categorial.set_categories (#57603)

* Add description to Index._to_numpy method.

* Fix description of default value for parameter "ordered" in set_categories

* Add description to return value of Categorical.set_categories and fix typo in description.

* Remove fixed docstrings from code_checks.sh

Author: bergnerjonas

Diff for: ci/code_checks.sh

@@ -1882,8 +1882,6 @@ if [[ -z "$CHECK" || "$CHECK" == "docstrings" ]]; then
 
     MSG='Partially validate docstrings (RT03)' ;  echo $MSG
     $BASE_DIR/scripts/validate_docstrings.py --format=actions --errors=RT03 --ignore_functions \
-        pandas.Index.to_numpy\
-        pandas.Categorical.set_categories\
         pandas.CategoricalIndex.set_categories\
         pandas.DataFrame.astype\
         pandas.DataFrame.at_time\

Diff for: pandas/core/arrays/categorical.py

@@ -1064,14 +1064,14 @@ def set_categories(
         On the other hand this methods does not do checks (e.g., whether the
         old categories are included in the new categories on a reorder), which
         can result in surprising changes, for example when using special string
-        dtypes, which does not considers a S1 string equal to a single char
+        dtypes, which do not consider a S1 string equal to a single char
         python string.
 
         Parameters
         ----------
         new_categories : Index-like
            The categories in new order.
-        ordered : bool, default False
+        ordered : bool, default None
            Whether or not the categorical is treated as a ordered categorical.
            If not given, do not change the ordered information.
         rename : bool, default False
@@ -1080,7 +1080,8 @@ def set_categories(
 
         Returns
         -------
-        Categorical with reordered categories.
+        Categorical
+            New categories to be used, with optional ordering changes.
 
         Raises
         ------

Diff for: pandas/core/base.py

@@ -566,6 +566,8 @@ def to_numpy(
         Returns
         -------
         numpy.ndarray
+            The NumPy ndarray holding the values from this Series or Index.
+            The dtype of the array may differ. See Notes.
 
         See Also
         --------