Merge pull request #253 from simon-liubin/master

7.0 sdk 文档调整
add mimetype spec of mkfile
Merge pull request #254 from forrest-mao/master

add mimetype spec of mkfile
Update avthumb.md
fix ueditor dn link
Merge pull request #255 from forrest-mao/master

fix ueditor dn link
魔法变量适用范围更改