Revert "添加分类算法综述及kNN和贝叶斯分类的PPT"

This reverts commit 04dec54daab59d40ef918e80b1bf1a7587c39531.
Revert "Revert "添加分类算法综述及kNN和贝叶斯分类的PPT""

This reverts commit 7d9e3db17ee745aa858d675e66c9992f096817a2.