add node logging documentation.

[GrothenDI]

Summary

• add a node logging guide covering default application logs and JVM garbage-collection logs
• document Logback routing, rotation, asynchronous queue behavior, Prometheus metric semantics, shutdown flushing, and custom configuration
• update the logging FAQ and add the guide to the site navigation

Why

The existing documentation did not provide a consolidated operator guide for node runtime logging. This change aligns the documentation with the logging behavior in java-tron GreatVoyage-v4.8.2 and clarifies how operators should locate, configure, and troubleshoot logs.

Impact

Node operators can identify the appropriate log file, understand retention and queue behavior, configure stdout and log levels safely, and distinguish Logback application logs from JVM GC logs.

Validation

• mkdocs build --strict
• git diff --check
• descriptions audited against the local java-tron source