[app][doc] append logging instructions
# ocrd_utils
-> OCR-D framework - shared code, helpers, constants
+Additional functionalities for OCR-D framework
See https://github.com/OCR-D/core
+
+
+## OCR-D Module Logging
+
+_Please note, that the following instructions only apply to the dockerized version of `ocrd_utils`._
+
+Configuration of Logging-Facilities is done with standard Python3 Logging Library from modul `logging`. This way, logging configuration can be customized for all OCR-D modules using the Python logging framework.
+A sample configuration file is included in the OCR-D container image at `/etc/ocrd_logging.conf`. This cofiguration is also meant to be the default configuration for OCR-D container images.
+If this file doesn't exist or gets removed, logging mechanics use as fallback the `logging.basicConfig` functionalities which use stdout as message channel.
+
+For more information about logging, handlers and formats, please see https://docs.python.org/3/howto/logging.htm.
+
+### Customization
+
+Create a custom Configuration and include this as part of your local workspace when running the OCR-D container.
+In this case, it will override *all* settings from default configuration, which is included at `/etc/ocrd_logging.conf`.
