[ImgBot] Optimize images
*Total -- 297.93kb -> 184.27kb (38.15%)
/docs/examples/images/Figure_9_2_m.png -- 25.24kb -> 14.53kb (42.44%)
/docs/examples/images/Figure_9_1_m.png -- 20.68kb -> 12.21kb (40.96%)
/docs/examples/images/Figure_9_1_a2.png -- 30.27kb -> 18.55kb (38.72%)
/docs/doc/images/example_4.png -- 30.27kb -> 18.55kb (38.72%)
/docs/examples/images/Figure_9_1_a1.png -- 95.73kb -> 60.21kb (37.1%)
/docs/doc/images/example_3.png -- 95.73kb -> 60.21kb (37.1%)
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