DOC minor typo fix in successive halving (scikit-learn#18601)

Author: NicolasHug

sklearn/model_selection/_search_successive_halving.py

@@ -394,7 +394,7 @@ class HalvingGridSearchCV(BaseSuccessiveHalving):
             - ``n_splits * 2`` when ``resource='n_samples'`` for a regression
                problem
             - ``n_classes * n_splits * 2`` when ``resource='n_samples'`` for a
-               regression problem
+               classification problem
             - ``1`` when ``resource != 'n_samples'``
         - 'exhaust' will set `r0` such that the **last** iteration uses as
           much resources as possible. Namely, the last iteration will use the
@@ -681,7 +681,7 @@ class HalvingRandomSearchCV(BaseSuccessiveHalving):
             - ``n_splits * 2`` when ``resource='n_samples'`` for a regression
                problem
             - ``n_classes * n_splits * 2`` when ``resource='n_samples'`` for a
-               regression problem
+               classification problem
             - ``1`` when ``resource != 'n_samples'``
         - 'exhaust' will set `r0` such that the **last** iteration uses as
           much resources as possible. Namely, the last iteration will use the