Fix typo

Fixes gh-1463

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/writer/DefaultGaugeService.java

@@ -29,7 +29,7 @@ public class DefaultGaugeService implements GaugeService {
 	private final MetricWriter writer;
 
 	/**
-	 * Create a {@link DefaultCounterService} instance.
+	 * Create a {@link DefaultGaugeService} instance.
 	 * @param writer the underlying writer used to manage metrics
 	 */
 	public DefaultGaugeService(MetricWriter writer) {