small fixes to be done to get closer to a valid BIDS dataset

[SylvainTakerkart]

Context:

• I'm running the BIDS generation using the BIDSDatasetBuilder as developed for confocal microscopy thanks to Microscopy confoncal and eyetracking customization parts #163
• I'm running the BIDS Validator (https://bids-standard.github.io/bids-validator/) on the generated dataset

List of small things to correct:

• generate only one README file instead of outputting several ones (README, README.md, README.rst, README.txt)
• add content to the following files because empty files are not allowed: README, samples.json, CHANGES, dataset_description.json, LICENSE, participants.json)
• add content to the Citation.cff file so that it respects the corresponding standard available here: https://github.com/citation-file-format/citation-file-format/blob/main/schema-guide.md
• remove genetic_info.json file