Documentation: list well-known property names for optional properties in SessionManagement.getConfiguration()

[danbim]

Define a set of fixed property names that is returned in the getConfigurationResponse type field options.

Currently, the Testbed Runtime implementation would need to return the hostname and port of the alternative Protocol Buffers based API: testbed.protobuf.hostname and testbed.protobuf.port.

[danbim]

Thinking about it again I don't think it's clever to enforce fixed property names in the API itself. However, I think they should be included in the documentation as well-known property names.

[danbim]

Changed issue title from Define fixed property names for optional properties in SessionManagement.getConfiguration() to Documentation: list well-known property names for optional properties in SessionManagement.getConfiguration()