Add logger configuration example to documentation

[tacman]

If it's possible to use another PSR-3 logger, can you update the documentation to reflect how that's done, and also how to adjust the debug level.

Ideally --verbose (and --v, -vv, -vvv) would control the router and worker output in some way, but at least configurating it to not display INFO calls would make the output more useful.

[tacman]

Is this even possible? In production, we'd like to run bin/console thruway:router:start and (1) turn off INFO and (2) use a custom Logger (send the logs to Graylog, for example).

It appears this is supported (voryx/Thruway#10), but I can't figure out how to pass in a Logger class (via services.yml) to the services that ThruwayBundle exposes.