[ImgBot] Optimize images (#41)

*Total -- 942.08kb -> 564.15kb (40.12%)

/slides/images/06_docker-logo.png -- 248.54kb -> 33.26kb (86.62%)
/slides/images/06_docker-lifecycle.png -- 236.59kb -> 155.35kb (34.34%)
/slides/images/02_api.png -- 46.97kb -> 32.96kb (29.84%)
/slides/images/02_presentation-layer.png -- 238.90kb -> 194.02kb (18.79%)
/slides/images/02_data-flow-chart.png -- 171.07kb -> 148.56kb (13.16%)

Signed-off-by: ImgBotApp <[email protected]>
Co-authored-by: ImgBotApp <[email protected]>

Author: imgbot[bot]