Add full example for `scijava_logger`

[ehrenfeu]

Expand the docstring with a complete example of how this is supposed to be used from within an ImageJ2 script, i.e.

• Header with #@ script parameter.
• Logging initialization (i.e. calling this function).
• Logging usage.

python-imcflibs/src/imcflibs/imagej/sjlog.py

Lines 7 to 20 in 357d60b

	def scijava_logger(log_service):
	"""Prepare logger and set the level according to stored ImageJ preferences.
	Parameters
	----------
	log_service : org.scijava.log.LogService
	The LogService instance, usually retrieved in a SciJava script by using
	the script parameters annotation `#@ LogService logs` or equivalent.
	Returns
	-------
	logger : logging.Logger
	The Python logger object connected to SciJava's LogService.
	"""