Add missing descriptions for HTTP Server and Data repositories metrics

See gh-31516

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/data/MetricsRepositoryMethodInvocationListener.java

@@ -83,8 +83,9 @@ public class MetricsRepositoryMethodInvocationListener implements RepositoryMeth
 		Set<Timed> annotations = TimedAnnotations.get(invocation.getMethod(), invocation.getRepositoryInterface());
 		Iterable<Tag> tags = this.tagsProvider.repositoryTags(invocation);
 		long duration = invocation.getDuration(TimeUnit.NANOSECONDS);
-		AutoTimer.apply(this.autoTimer, this.metricName, annotations, (builder) -> builder.tags(tags)
-				.register(this.registrySupplier.get()).record(duration, TimeUnit.NANOSECONDS));
+		AutoTimer.apply(this.autoTimer, this.metricName, annotations,
+				(builder) -> builder.description("Duration of repository invocations").tags(tags)
+						.register(this.registrySupplier.get()).record(duration, TimeUnit.NANOSECONDS));
 	}
 
 }

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/reactive/server/MetricsWebFilter.java

@@ -109,7 +109,8 @@ public class MetricsWebFilter implements WebFilter {
 			Iterable<Tag> tags = this.tagsProvider.httpRequestTags(exchange, cause);
 			long duration = System.nanoTime() - start;
 			AutoTimer.apply(this.autoTimer, this.metricName, annotations,
-					(builder) -> builder.tags(tags).register(this.registry).record(duration, TimeUnit.NANOSECONDS));
+					(builder) -> builder.description("Duration of HTTP server request handling").tags(tags)
+							.register(this.registry).record(duration, TimeUnit.NANOSECONDS));
 		}
 		catch (Exception ex) {
 			logger.warn("Failed to record timer metrics", ex);

spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/web/servlet/WebMvcMetricsFilter.java

@@ -158,7 +158,8 @@ public class WebMvcMetricsFilter extends OncePerRequestFilter {
 
 	private Timer getTimer(Builder builder, Object handler, HttpServletRequest request, HttpServletResponse response,
 			Throwable exception) {
-		return builder.tags(this.tagsProvider.getTags(request, response, handler, exception)).register(this.registry);
+		return builder.description("Duration of HTTP server request handling")
+				.tags(this.tagsProvider.getTags(request, response, handler, exception)).register(this.registry);
 	}
 
 	/**