[ImgBot] Optimize images

*Total -- 179.58kb -> 149.62kb (16.68%)

/images/github_icon.jpg -- 1.55kb -> 0.41kb (73.77%)
/images/github_icon.png -- 1.67kb -> 1.08kb (35.65%)
/images/logo.jpg -- 176.36kb -> 148.14kb (16%)

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

Author: ImgBotApp