[ImgBot] Optimize images

*Total -- 93.98kb -> 49.53kb (47.29%)

/img/窗口截图.png -- 11.93kb -> 6.20kb (48.04%)
/img/高DPI设置.png -- 82.05kb -> 43.33kb (47.18%)

Signed-off-by: ImgBotApp <ImgBotHelp@gmail.com>

Author: ImgBotApp