deleted comma
Added dates to websites according the respective website, checked links, updated urldates, added "author = {VIVO Project}" to the references of "About Vitro" and "VIVO-ISF-Ontology", changes "Vivo-isf-ontology" to "VIVO-ISF-Ontology".
Bibliography in bibtex format for paper.md, a short paper submitted to the Journal of Open Source Software