[ImgBot] Optimize images

*Total -- 3,347.33kb -> 3,115.37kb (6.93%)

/openfaas-function/docs/litellm-sample.png -- 27.41kb -> 20.66kb (24.63%)
/docs/searxng-homepage.png -- 541.79kb -> 412.26kb (23.91%)
/docs/search_llm_assist.png -- 421.30kb -> 400.62kb (4.91%)
/docs/videos/pipe_mcts.gif -- 2,356.84kb -> 2,281.84kb (3.18%)

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

Author: ImgBotApp