Update README.md

Musical Heritage Historical named Entities Recognition, Classification and Linking (MHERCL) is a benchmark on Named Entity Recognition and Entity Linking on historical documents focused in the music domain.
It contains manually annotated sentences extrapolated from the Polifonia Corpus, a diachronic and multilingual corpus specialized in the music domain. Documents whose publication dates range from 1823 to 1900, are used as the set of sentences within MHERCL.

README.md

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+license: cc-by-4.0
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