Update example plugin for API changes in #103277 (#104357)

Author: thecoop

plugins/examples/rest-handler/src/main/java/org/elasticsearch/example/resthandler/ExampleRestHandlerPlugin.java

@@ -10,6 +10,7 @@
 
 import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
 import org.elasticsearch.cluster.node.DiscoveryNodes;
+import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
 import org.elasticsearch.common.settings.ClusterSettings;
 import org.elasticsearch.common.settings.IndexScopedSettings;
 import org.elasticsearch.common.settings.Settings;
@@ -28,6 +29,7 @@ public class ExampleRestHandlerPlugin extends Plugin implements ActionPlugin {
 
     @Override
     public List<RestHandler> getRestHandlers(final Settings settings,
+                                             final NamedWriteableRegistry namedWriteableRegistry,
                                              final RestController restController,
                                              final ClusterSettings clusterSettings,
                                              final IndexScopedSettings indexScopedSettings,