Fix Javadoc @Since checkstle violations

Apply consistent `@Since` tags and retrofit the existing code using a
best guess from the git history.

Closes gh-17360

spring-boot-docs/src/main/java/org/springframework/boot/kafka/KafkaSpecialProducerConsumerConfigExample.java

@@ -36,7 +36,7 @@ import org.springframework.kafka.core.ProducerFactory;
  * common properties to the producer and consumer.
  *
  * @author Gary Russell
- * @since 1.5
+ * @since 1.5.0
  */
 public class KafkaSpecialProducerConsumerConfigExample {