[ImgBot] Optimize images (#222)

*Total -- 1,393.88kb -> 908.68kb (34.81%)

/doc/assets/chrome_confirm.png -- 34.10kb -> 18.95kb (44.43%)
/doc/assets/server-password-modal.png -- 96.67kb -> 58.14kb (39.86%)
/doc/assets/ide.png -- 984.53kb -> 603.38kb (38.71%)
/doc/assets/chrome_warning.png -- 44.25kb -> 30.03kb (32.14%)
/doc/assets/logo-horizontal.png -- 22.00kb -> 17.48kb (20.55%)
/doc/assets/aws_ubuntu.png -- 51.62kb -> 43.93kb (14.91%)
/doc/assets/cli.png -- 160.70kb -> 136.78kb (14.89%)