Include Jetty metrics in list of supported metrics

Closes gh-27299

Author: wilkinsona

spring-boot-project/spring-boot-docs/src/docs/asciidoc/production-ready-features.adoc

@@ -2123,6 +2123,7 @@ Spring Boot registers the following core metrics when applicable:
 ** Number of classes loaded/unloaded
 * CPU metrics
 * File descriptor metrics
+* Jetty metrics
 * Kafka consumer, producer, and streams metrics
 * Log4j2 metrics: record the number of events logged to Log4j2 at each level
 * Logback metrics: record the number of events logged to Logback at each level
@@ -2384,6 +2385,12 @@ For more details refer to {spring-kafka-docs}#micrometer-native[Micrometer Nativ
 
 
 
+[[production-ready-metrics-jetty]]
+==== Jetty Metrics
+Auto-configuration will bind metrics for Jetty's `ThreadPool` using Micrometer's `JettyServerThreadPoolMetrics`.
+
+
+
 [[production-ready-metrics-custom]]
 === Registering custom metrics
 To register custom metrics, inject `MeterRegistry` into your component, as shown in the following example: