[ImgBot] Optimize images

*Total -- 1,159.93kb -> 918.50kb (20.81%)

/css-crash-course/images/box-model.jpg -- 57.53kb -> 43.86kb (23.75%)
/css-flexbox-course/images/baseline.jpg -- 260.92kb -> 200.96kb (22.98%)
/html-crash-course/layout.jpg -- 63.07kb -> 48.97kb (22.36%)
/css-crash-course/images/inspector.jpg -- 172.48kb -> 134.25kb (22.17%)
/css-crash-course/images/relative-units.jpg -- 225.40kb -> 178.53kb (20.8%)
/css-crash-course/images/absolute-units.jpg -- 93.41kb -> 74.22kb (20.54%)
/css-flexbox-course/images/flexbox-axes.jpg -- 81.80kb -> 66.47kb (18.75%)
/css-grid-course/images/grid-line-cell-track-area.jpg -- 50.87kb -> 41.68kb (18.08%)
/css-flexbox-course/images/flexbox-container-and-items.jpg -- 77.47kb -> 64.15kb (17.2%)
/css-grid-course/images/grid-container-and-grid-items.jpg -- 76.97kb -> 65.42kb (15%)

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

Author: ImgBotApp