`simple-logger` dependency should be documented or removed

[gabrielfeo]

The library ships with simple-logger instead of relying on the consumer to provide SLF4J bindings. This was intentional to provide out-of-the-box logging using the library from notebooks and scripts. However, it's not obvious when using the library from projects.

Fix options

1. Document it in the README and suggest excluding simple-logger in the example dependencies snippet (unintuitive for projects)
2. Remove simple-logger and logLevel functionality (very unintuitive for notebooks and scripts)