[ImgBot] Optimize images

*Total -- 1,713.52kb -> 1,113.74kb (35%)

/docs/databases-cloudant.png -- 226.19kb -> 95.67kb (57.7%)
/docs/after-cors.png -- 620.84kb -> 390.41kb (37.12%)
/docs/before-cors.png -- 866.49kb -> 627.65kb (27.56%)

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

Author: ImgBotApp