Documentation improvements

-m parameter help text: Mention that these are Prometheus metrics, to point the uninitiated into the right direction.

The log list used should be documented in the readme, not in the -help output. In the -help output I'm looking for the CLI arguments and general usage info, but the log list can't be configured via argument. (It's awesome that the log list is fetched automatically! I'm wondering if it's also self-updating if I run the server over a year?)

I assume the internal state is serialised to disk periodically to limit the redundant work on a crash. Is this even needed, or is anything important on disk anyway? It might be nice to explicitly document this.