[ImgBot] Optimize images

*Total -- 37,481.46kb -> 30,979.61kb (17.35%)

/examples/CommandCenter.png -- 6,942.98kb -> 4,947.75kb (28.74%)
/examples/Infographic.png -- 7,532.81kb -> 5,502.86kb (26.95%)
/examples/frogs.png -- 7,304.68kb -> 5,572.13kb (23.72%)
/examples/sample_input.png -- 79.34kb -> 66.50kb (16.19%)
/examples/sample_input_compare.png -- 278.91kb -> 256.54kb (8.02%)
/examples/Infographic_compare.png -- 8,082.06kb -> 7,689.89kb (4.85%)
/examples/CommandCenter_compare.png -- 7,260.68kb -> 6,943.95kb (4.36%)

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

Author: ImgBotApp