Polish "Add metric description and base unit to metrics endpoint"

Closes gh-13813

Author: snicoll

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/endpoint/web/documentation/MetricsEndpointDocumentationTests.java

@@ -54,7 +54,8 @@ public void metric() throws Exception {
 				.andExpect(status().isOk())
 				.andDo(document("metrics/metric", responseFields(
 						fieldWithPath("name").description("Name of the metric"),
-						fieldWithPath("description").description("Description of the metric"),
+						fieldWithPath("description")
+								.description("Description of the metric"),
 						fieldWithPath("baseUnit").description("Base unit of the metric"),
 						fieldWithPath("measurements")
 								.description("Measurements of the metric"),