DOC Fix reference in whats new 0.21 (scikit-learn#13845)

Author: thomasjpfan

doc/modules/classes.rst

@@ -346,6 +346,7 @@ Samples generator
    decomposition.dict_learning
    decomposition.dict_learning_online
    decomposition.fastica
+   decomposition.non_negative_factorization
    decomposition.sparse_encode
 
 .. _lda_ref:

doc/whats_new/v0.21.rst

@@ -38,7 +38,7 @@ random sampling procedures.
   seed, including :class:`linear_model.LogisticRegression`,
   :class:`linear_model.LogisticRegressionCV`, :class:`linear_model.Ridge`,
   and :class:`linear_model.RidgeCV` with 'sag' solver. |Fix|
-- :class:`linear_model.ridge.RidgeCV` when using generalized cross-validation
+- :class:`linear_model.RidgeCV` when using generalized cross-validation
   with sparse inputs. |Fix|
 
 
@@ -510,7 +510,7 @@ Support for Python 3.4 and below has been officially dropped.
   in version 0.21 and will be removed in version 0.23.
   :pr:`12821` by :user:`Nicolas Hug <NicolasHug>`.
 
-- |Fix| :class:`linear_model.ridge.RidgeCV` with generalized cross-validation
+- |Fix| :class:`linear_model.RidgeCV` with generalized cross-validation
   now correctly fits an intercept when ``fit_intercept=True`` and the design
   matrix is sparse. :issue:`13350` by :user:`Jérôme Dockès <jeromedockes>`
 
@@ -587,11 +587,11 @@ Support for Python 3.4 and below has been officially dropped.
   in version 0.21 and will be removed in version 0.23. :pr:`10580` by
   :user:`Reshama Shaikh <reshamas>` and :user:`Sandra Mitrovic <SandraMNE>`.
 
-- |Fix| The function :func:`euclidean_distances`, and therefore
-  several estimators with ``metric='euclidean'``, suffered from numerical
-  precision issues with ``float32`` features. Precision has been increased at the
-  cost of a small drop of performance. :pr:`13554` by :user:`Celelibi` and
-  :user:`Jérémie du Boisberranger <jeremiedbb>`.
+- |Fix| The function :func:`metrics.pairwise.euclidean_distances`, and 
+  therefore several estimators with ``metric='euclidean'``, suffered from 
+  numerical precision issues with ``float32`` features. Precision has been 
+  increased at the cost of a small drop of performance. :pr:`13554` by 
+  :user:`Celelibi` and :user:`Jérémie du Boisberranger <jeremiedbb>`.
 
 - |API| :func:`metrics.jaccard_similarity_score` is deprecated in favour of
   the more consistent :func:`metrics.jaccard_score`. The former behavior for