Add statsd monitor documentation

[Evian-Zhang]

Currently, this is a Draft PR. I will finish this asap. There have been several busy weeks for me, so I may be slow to respond and update.

[domenukk]

Already looks good, we can merge this for now if you want?

[Evian-Zhang]

There are still plenty of key contents missing. A grafana dashboard template should be added to help visualizing the data, and I will add a screenshot and several FAQs sooner. Maybe a few days later I could complete this. (Life is hard for a PhD candidate😂)

[domenukk]

Thanks for doing it in any case! Happy to merge this whenever you feel like it

[Evian-Zhang]

I have completed the doc for StatsdMonitor. Please feel free to review this PR. :)

[tokatoka]

why libfuzzer_stb_image_sugar always fails at your branch 😂
yes the script is bad for false positives but it's very rare for us to hit that failure

[Evian-Zhang]

Maybe GitHub uses different runner machines based on user location? It's indeed weird, though😆

[Evian-Zhang]

I think the CI checks are all passed. If there are still something to improve, feel free to review my PR :)

[domenukk]

Thank you!