[Task]: Explain how logging using slf4j can be set up

### What needs to happen?

Migration: https://issues.apache.org/jira/browse/HOP-3894

in the backend slf4j is also used, so you can attach your own logger and config file if needed
you can replace the slf4j-nop with slf4j-log4j for example and add a log4j config
and if you are piping stdout/stderr on the server you can {{mycommand &> "$(date +%Y-%m-%d_%H-%M-%S.txt)"}}

### Issue Priority

Priority: 3

### Issue Component

Component: Documentation

Start by locating the backend logging documentation and the project's SLF4J dependency configuration. Explain how to replace slf4j-nop with slf4j-log4j, add a Log4j configuration, and redirect server stdout/stderr; done when these setup options are documented clearly for backend users.

Written by the indexing model from the issue text.