DOC some fixes to the doc build.

doc/datasets/rcv1.rst

doc/modules/decomposition.rst

doc/modules/feature_selection.rst

doc/modules/multiclass.rst

doc/whats_new.rst

examples/applications/face_recognition.py

sklearn/cross_decomposition/pls_.py

sklearn/datasets/descr/breast_cancer.rst

sklearn/datasets/descr/diabetes.rst

sklearn/datasets/descr/digits.rst

sklearn/datasets/descr/iris.rst

sklearn/linear_model/base.py

sklearn/preprocessing/data.py

sklearn/preprocessing/tests/test_data.py