[ImgBot] Optimize images (#380)

*Total -- 40.04kb -> 27.97kb (30.14%)

/docs/images/RunningTree.svg -- 21.53kb -> 14.50kb (32.67%)
/docs/images/FallbackBasic.svg -- 18.51kb -> 13.48kb (27.2%)

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

Co-authored-by: ImgBotApp <ImgBotHelp@gmail.com>

Author: imgbot[bot]