audd-rust: 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

@@ -290,8 +290,8 @@ If hosting a callback receiver isn't an option, longpoll for events from the cli
 use futures_util::StreamExt;
 
 # async fn run(audd: AudD) -> Result<(), audd::AudDError> {
-let category = audd.streams().derive_longpoll_category(1); // computed locally
-let mut poll = audd.streams().longpoll(&category, LongpollOptions::default()).await?;
+let radio_id = 1i64; // any integer you choose — your handle for this stream
+let mut poll = audd.streams().longpoll_by_radio_id(radio_id, LongpollOptions::default()).await?;
 
 loop {
     tokio::select! {