[ImgBot] Optimize images

*Total -- 317.02kb -> 235.13kb (25.83%)

/demo/v2-demo/images/sampleqna.png -- 59.21kb -> 21.66kb (63.43%)
/demo/code-demo/images/clear.png -- 1.27kb -> 0.85kb (33%)
/demo/v2-demo/images/sampledashboard.png -- 100.03kb -> 79.96kb (20.06%)
/demo/v2-demo/images/samplereport.png -- 54.33kb -> 43.88kb (19.23%)
/demo/v2-demo/images/samplevisual.png -- 10.66kb -> 9.24kb (13.32%)
/demo/v2-demo/images/sampletile.png -- 91.53kb -> 79.55kb (13.09%)

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

Author: ImgBotApp