reorganization of README sections (added some as suggestions too)
added badges generated by HUMG (+ integrated in README)
HUMG also updated metrics in htr-united.yml
added a CC-BY 4.0 LICENSE to match info in README, although I would suggest clarifying what applies to what (right now you say the transcription are copyright free but the image are under Heidelberg's library copyright, yet the dataset is under CC-BY)
added placeholder for a folder of static images, to add illustrations of the dataset, the transcription guidelines and any other logos