esap-general#92

- Use the singular (you can only select one from each list; you can't select
  "workflows");
- Simplifying wording (nobody needs to see “ESFRI” here!).

These services are not all JupyterHub systems. Indeed, at time of writing the
only service we've actually configured in esap-api-gateway is MyBinder, which
isn't a JupyterHub at all. Calling them “jhub” or similar is going to cause
confusion.