[ImgBot] Optimize images

*Total -- 978.23kb -> 656.96kb (32.84%)

/workshop/.gitbook/generic/gitbook-logo.png -- 31.59kb -> 18.70kb (40.8%)
/workshop/.gitbook/generic/gitbook-theme-and-color.png -- 64.38kb -> 40.61kb (36.93%)
/workshop/.gitbook/generic/gitbook-mainstructure.png -- 882.26kb -> 597.65kb (32.26%)

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Author: ImgBotApp