COSMIT various typofixes

doc/datasets/index.rst

doc/developers/index.rst

doc/developers/performance.rst

doc/modules/decomposition.rst

doc/modules/dp-derivation.rst

doc/modules/ensemble.rst

doc/modules/feature_extraction.rst

doc/modules/gaussian_process.rst

doc/modules/kernel_approximation.rst

doc/modules/lda_qda.rst

doc/modules/linear_model.rst

doc/modules/model_evaluation.rst

doc/modules/outlier_detection.rst

doc/modules/sgd.rst

examples/applications/plot_outlier_detection_housing.py

examples/cluster/plot_digits_agglomeration.py

examples/cluster/plot_kmeans_digits.py

examples/cluster/plot_segmentation_toy.py

examples/covariance/plot_mahalanobis_distances.py

examples/decomposition/plot_sparse_coding.py