DOC some fixes to the doc build.

doc/datasets/index.rst

doc/datasets/rcv1.rst

doc/modules/decomposition.rst

doc/modules/feature_selection.rst

doc/modules/gaussian_process.rst

doc/modules/multiclass.rst

doc/modules/neural_networks_supervised.rst

doc/modules/outlier_detection.rst

doc/whats_new.rst

examples/applications/face_recognition.py

examples/gaussian_process/plot_gpr_co2.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/datasets/kddcup99.py

sklearn/gaussian_process/gpc.py

sklearn/gaussian_process/gpr.py

sklearn/gaussian_process/kernels.py