Add config option to sphinx extension to blacklist datasets from showing example on the datacard

[hagenw]

At the moment, you can configure per TOC entry if audio examples should be shown on a datacard. In addition, they are only shown if a dataset contains a file that has at least one file with a duration of >0.5 s and <300s:

audbcards/audbcards/core/datacard.py

Lines 98 to 100 in d2510ee

	# Pick a meaningful duration for the example audio file
	min_dur = 0.5
	max_dur = 300 # 5 min

But you might still have the problem, that you have datasets that should not be accessibly by all users that can view a datacard. For those it would be good to disable showing an audio example. Another reason might be if all media files are stored in a single (or only a few) archives, as then the whole dataset needs to be downloaded in audb cache just to get a single media example.

To solve this, I would propose to add an config option, that a user can set inside docs/dong.py, e.g. audbcard_datasets_to_exclude_example.