Changes to get list of known x-road instance identifiers

the items response property's maxLength was unset from 255 for the response status 200

the items response property's minLength was decreased from 1 to 0 for the response status 200

the items response's property type changed from string to object, and format from text to no format for status 200

api operation id getXroadInstances removed and replaced with getXRoadInstances

api tag x-road-instances added

api tag xroad-instances removed

added the required property items/identifier to the response with the 200 status

added the required property items/local to the response with the 200 status