[ImgBot] Optimize images

*Total -- 1,024.19kb -> 724.15kb (29.3%)

/src/readme1.png -- 147.47kb -> 86.92kb (41.06%)
/src/readme2.png -- 92.94kb -> 60.81kb (34.57%)
/src/image3.png -- 244.75kb -> 174.15kb (28.85%)
/src/readme3.png -- 519.70kb -> 386.64kb (25.6%)
/src/image1.png -- 19.33kb -> 15.63kb (19.17%)

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

Author: ImgBotApp