audd-java: README — switch longpoll example to one-step form

Main longpoll example uses the new one-step entry point added in the SDK's most recent release. The 2-step derive_longpoll_category → longpoll(category) form stays documented under the 'Tokenless consumers' section, where it's the right tool: a server with the api_token derives the category and ships only the 9-char string to a browser/mobile/embedded client.

Author: AudD

README.md

@@ -284,8 +284,8 @@ drive a blocking dispatch loop:
 ```java
 import io.audd.streams.LongpollPoll;
 
-String category = audd.streams().deriveLongpollCategory(1234);
-try (LongpollPoll poll = audd.streams().longpoll(category)) {
+long radioId = 1L; // any integer you choose — your handle for this stream
+try (LongpollPoll poll = audd.streams().longpoll(radioId)) {
     poll.onMatch(m -> System.out.println(m.song().artist() + " — " + m.song().title()));
     poll.onNotification(n -> System.out.println("notif: " + n.notificationMessage()));
     poll.onError(err -> System.err.println(err));