Add CPU usage metrics (#2043)

The corresponding PRs are
neo-technology/neo4j#28128 and
https://github.com/neo-technology/neo4j/pull/28439/files

---------

Co-authored-by: Fábio Botelho <[email protected]>

Author: NataliaIvakina

modules/ROOT/pages/monitoring/metrics/reference.adoc

@@ -500,15 +500,29 @@ label:deprecated[Deprecated in 5.15]
 [[jvm-metrics]]
 == Java Virtual Machine Metrics
 
-The JVM metrics show information about garbage collections (for example, the number of events and time spent collecting), memory pools and buffers, and the number of active threads running.
+The JVM metrics show information about garbage collections (for example, the number of events and time spent collecting), memory pools and buffers, the number of active threads running, and the usage of central processing unit (CPU) for the Neo4j process and operating system.
 They are environment dependent and therefore, may vary on different hardware and with different JVM configurations.
+
 The metrics about the JVM's memory usage expose values that are provided by the MemoryPoolMXBeans and BufferPoolMXBeans.
 The memory pools are memory managed by the JVM, for example, `neo4j.dbms.vm.memory.pool.g1_survivor_space`.
 Therefore, if necessary, you can tune them using the JVM settings.
+
 The buffer pools are space outside of the memory managed by the garbage collector.
 Neo4j allocates buffers in those pools as it needs them.
 You can limit this memory using JVM settings, but there is never any good reason for you to set them.
 
+[role=label--new-2025.01]
+[[cpu-usage-metrics]]
+=== CPU usage metrics
+
+.CPU usage metrics
+[options="header",cols="<3m,<4"]
+|===
+|Name |Description
+|<prefix>.vm.cpu_load.system|The recent CPU usage for the operating system. This value is a double in the [0.0, 1.0] interval. Depending on the Java distribution you use, the metric may be unavailable. (gauge)
+|<prefix>.vm.cpu_load.process|The recent CPU usage for the Neo4j process. This value is a double in the [0.0, 1.0] interval. Depending on the Java distribution you use, the metric may be unavailable. (gauge)
+|===
+
 [[jvm-file-descriptor-metrics]]
 === JVM file descriptor metrics