Update README.md

finish UMAP

add UMAP uniform manifold approximation and projection algorighm introduction

ISLR chapter4 question11 compare LDA, QDA, Logistics regression, knn on test error

add ISLR(introduction to statistical learning with application in R) Chapter4 question 10 compare KNN, LDA, QDA, Logistics regression

modify QDA.md logistics regression assump that X|c is exponential distribution

modify QDA.md

modify README.md

modify README.md

finish QDA

modify LDA.md

give LDA classifier probability explanation and add QDA

modify LDA.md

modify LDA.md

finish LDA and compare LDA with PCA