[ImgBot] Optimize images
*Total -- 118.88kb -> 86.77kb (27.01%)
/docs/images/spectrafit_synopsis.png -- 56.15kb -> 34.42kb (38.7%)
/docs/examples/images/Figure_5.png -- 60.42kb -> 50.17kb (16.97%)
/docs/images/logo.svg -- 2.32kb -> 2.18kb (5.65%)
Signed-off-by: ImgBotApp <ImgBotHelp@gmail.com>
