update build/README.md
Add notice section.
Merge branch 'generate_ebook'
update README.md, 添加中文提示
Merge pull request #133 from marchtea/master

修改README.md, 增加使用脚本的提示
fix chapter 03.04 incorrect img url format
Update 03.04.md
remove all ?raw=true in img links
Merge remote-tracking branch 'up/master'