chore: fix Javadoc (a2aproject#701)

Signed-off-by: Jeff Mesnil <jmesnil@ibm.com>

Author: jmesnil

transport/grpc/src/main/java/io/a2a/transport/grpc/handler/GrpcHandler.java

@@ -96,7 +96,7 @@
  *   <li>{@link #listTasks} - List tasks with filtering</li>
  *   <li>{@link #createTaskPushNotificationConfig} - Configure push notifications</li>
  *   <li>{@link #getTaskPushNotificationConfig} - Get push notification config</li>
- *   <li>{@link #listTaskPushNotificationConfig} - List push notification configs</li>
+ *   <li>{@link #listTaskPushNotificationConfigs} - List push notification configs</li>
  *   <li>{@link #deleteTaskPushNotificationConfig} - Delete push notification config</li>
  *   <li>{@link #getExtendedAgentCard} - Get extended agent capabilities</li>
  * </ul>