[High-Level-API] Update MNIST to use optimizer_func

[High-Level-API] Add the Chinese veriosn of the recognize digits.

[High-Level-API] Rewrite Chapter 5 Personalized Recommendation in Book to use new Flui…

[High-Level-API] Image classification train.py update

Recognize digits new api 2

Recognize digits new api first draft

fix deadlinks in index.html and index.cn.html

fix deadline in machine_translation/README.cn.md

update docs

fix math formula bug

fix quick start for fluid, add model tar #9660

update IP to new node