Create ontology repository

[prjemian]

As discussed in today's telco, we could create a new repository in this GitHub organization to host the script-generated ontology files. This would happen on every push to the main branch. Tags in this repo would be created on the ontology repo as well. Tags in the ontology repo could push the versioned ontology to a public service so that is findable.

The published ontology describes the NeXus standard, it does not define the standard.

Originally posted by @prjemian in #879 (comment)

[prjemian]

Suggest creating https://github.com/nexusformat/NeXusOntology as the new repo.

[prjemian]

Also, only create & tag ontologies for definitions tags that start with "v" so we do not create ontologies for every update or even new tags of application definition versions.

[prjemian]

Expecting a domain for this on https://purl.org

[prjemian]

Repository is now created. We'll need a script (Github Actions workflow) to create the new content and a to push it to the main branch on https://github.com/nexusformat/NeXusOntology. Also, the script should create a matching tag on the new repo for any new tag here that starts with the letter v (signifying a new tagged release of the NeXus definitions). We should avoid tags with rc in the name since these mark release candidates and are not final releases.