initial content and ReadMe

Added original Excel-files and ReadMe cfr. data available on
https://code.google.com/archive/p/freshwatercore/

README.md

+# freshwaterCore
+Darwin Core field description and selection for use in the BioFresh project, the Freshwater Biodiversity Data Portal, SAFRED and freshwater sciences at large.
+
+Detailed description and selection of fields for use in the data templates as originally developed for the BioFresh project and data portal [http://data.freshwaterbiodiversity.eu/](http://data.freshwaterbiodiversity.eu/). This GitLab project is intended to update the description and turn in into a “DwC recipe” in the framework of the SAFRED (Saving Freshwater Biodiversity Research Data - [http://odnature.naturalsciences.be/safred/](http://odnature.naturalsciences.be/safred/)) project.
+
+Tags: Biodiversity, DarwinCore, Freshwater, Template
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