Add another dependency required for javadoc generation with Java 9

See gh-10515

spring-boot-project/spring-boot-docs/pom.xml

@@ -241,6 +241,11 @@
 			<artifactId>micrometer-registry-prometheus</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>io.micrometer</groupId>
+			<artifactId>micrometer-registry-statsd</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>io.projectreactor.ipc</groupId>
 			<artifactId>reactor-netty</artifactId>