Create best-practices on version-compatibility and deployment on subdomains

[arnoweiss]

The versioning mechanism in the DSP is not self-explanatory. Provider-side deployment decisions on URL structuring can complicate the setup but all leave robust navigation for Consumers. We should come up with a set of deployment best-practices for the Provider.

[arnoweiss]

There's a couple of dimensions to this:

1. single vs multiple Catalog endpoints
2. single vs multiple Negotiation endpoints
3. API-Gateway - yes or no