Fix description of management.metrics.export.influx.db

Closes gh-25723

Author: snicoll

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/export/influx/InfluxProperties.java

@@ -33,7 +33,7 @@
 public class InfluxProperties extends StepRegistryProperties {
 
 	/**
-	 * Tag that will be mapped to "host" when shipping metrics to Influx.
+	 * Database to send metrics to.
 	 */
 	private String db = "mydb";