chore(openapi): document serving of public api only

Co-authored-by: Johannes Wienke <[email protected]>

Author: nkoester

model-server/src/main/kotlin/org/modelix/model/server/Main.kt

@@ -240,6 +240,7 @@ object Main {
                             call.respondText("SwaggerUI is disabled")
                         }
                     } else {
+                        // we only serve the public API to the outside via swagger UI
                         swaggerUI(path = "swagger", swaggerFile = "../api/model-server.yaml")
                     }
                 }