MRG Sphinx fixes (#9155)

doc/faq.rst

doc/tutorial/statistical_inference/putting_together.rst

doc/tutorial/statistical_inference/supervised_learning.rst

doc/whats_new.rst

examples/applications/plot_topics_extraction_with_nmf_lda.py

sklearn/covariance/graph_lasso_.py

sklearn/covariance/tests/test_graph_lasso.py

sklearn/ensemble/iforest.py

sklearn/feature_extraction/hashing.py

sklearn/linear_model/bayes.py

sklearn/linear_model/least_angle.py

sklearn/linear_model/ransac.py

sklearn/linear_model/stochastic_gradient.py

sklearn/manifold/t_sne.py

sklearn/mixture/bayesian_mixture.py

sklearn/mixture/gaussian_mixture.py

sklearn/model_selection/_split.py

sklearn/model_selection/_validation.py

sklearn/utils/extmath.py

sklearn/utils/validation.py