I have listed all the major tags representing the different major endpoints from the Orthanc REST API.
As you know, it will take some time to fully flesh out the OpenAPI specficiation.
Currently, it has a complete working spec of the /changes endpoint.
I think via community contribution via forks (and any free time that I have) we can complete this task.
I think as Orthanc project lead, you should audit the spec and make any necessary changes you feel that are relevant. There are a number of additional objects and fields that could be implemented in the spec that I have chosen not to include for the sake of brevity.