vivo/rdf/tbox/filegraph/README.md

I believe this directory is where you would add serialized RDF to be automatically loaded when VIVO bootstraps.

@brianjlowe does a great job of describing these files, and pointing out some highlights. I did a poor job of capturing this information in realtime, but this pull request is my bookmark to follow up.

Action Items:

• capture highlights covered by @brianjlowe in #vivoifest15 session
• identify best place to document all of the existing files in this directory, e.g. a table in this Markdown doc versus in the files themselves?
• identify where to document @ShahimEssaid recommendations regarding best practices for local ontology extensions:

• Don't create without discussing use case with vivo ontology mailing list on sourceforge -- new classes and new properties
• Don't re-use existing vocab to VIVO-ISF mailing list