[ImgBot] Optimize images

*Total -- 818.24kb -> 710.91kb (13.12%)

/images/favicon.png -- 269.96kb -> 196.40kb (27.25%)
/images/plasma-522-altai.jpg -- 548.28kb -> 514.50kb (6.16%)

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

Author: ImgBotApp