Figure out how to access and display a specific version (release)

[AndyClifton]

Each change to the spreadsheet of definitions creates a new version of the ontology. For traceability it would be useful to be able to reference a specific version.

This could be done using Github's 'release' functionality, and then results could be visualized using the SKOS Play tools - https://skos-play.sparna.fr/play/.

This needs to be tested.