docs: Add cleanup policy overview

[julealgon]

The main documentation for this sink does not properly explain how the sinks are cleaned up once the limit is reached. I spent some time looking at the code to see how it was disposing the sinks because this was important to my application from a performance standpoint.

Can we add more information related to the cleanup process:

• Is the process deterministic?
• In what order are sinks disposed once the limit is reached?
• Does the cleanup happen asynchronously, or synchronously?
• When exactly cleanup attempts are made? Before or after the next event is logged?

Having this information upfront would've saved me a few hours of testing and investigation, so I believe this could prove useful for other folks as well.

[nblumhardt]

Hi Juliano,

Thanks for investigating! Yes, this documentation would be useful/welcome, thanks 👍

[nblumhardt]

Closing this one as stale; doc contributions still welcome if anyone's interested in picking it up.