KAFKA-7198: Enhance KafkaStreams start method javadoc. (#5763)

Reviewers: Bill Bejeck <[email protected]>, Matthias J. Sax <[email protected]>

streams/src/main/java/org/apache/kafka/streams/KafkaStreams.java

@@ -765,6 +765,7 @@ private static HostInfo parseHostInfo(final String endPoint) {
      * This function is expected to be called only once during the life cycle of the client.
      * <p>
      * Because threads are started in the background, this method does not block.
+     * However, if you have global stores in your topology, this method blocks until all global stores are restored.
      * As a consequence, any fatal exception that happens during processing is by default only logged.
      * If you want to be notified about dying threads, you can
      * {@link #setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler) register an uncaught exception handler}