refactor: harmonize method names

examples/relay/main.cpp

@@ -23,7 +23,7 @@ void setup() {
     
     // Create and add custom service
     relayService = new RelayService(spore.getContext(), spore.getTaskManager(), RELAY_PIN);
-    spore.addService(relayService);
+    spore.registerService(relayService);
     
     // Start the API server and complete initialization
     spore.begin();