api: add to cpu speed parameter a description of the cgroup2 case (#9191)

This PR adds to the cpuSpeed parameter of CreateServiceOfferingCmd a description how it will be interpreted in the case cgroups are being used on KVM.

Fixes: #6743

Co-authored-by: Bryan Lima <42067040+BryanMLima@users.noreply.github.com>

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Co-authored-by: Bryan Lima <42067040+BryanMLima@users.noreply.github.com>

Author: DaanHoogland

api/src/main/java/org/apache/cloudstack/api/command/admin/offering/CreateServiceOfferingCmd.java

@@ -56,7 +56,11 @@ public class CreateServiceOfferingCmd extends BaseCmd {
     @Parameter(name = ApiConstants.CPU_NUMBER, type = CommandType.INTEGER, required = false, description = "the CPU number of the service offering")
     private Integer cpuNumber;
 
-    @Parameter(name = ApiConstants.CPU_SPEED, type = CommandType.INTEGER, required = false, description = "the CPU speed of the service offering in MHz.")
+    @Parameter(name = ApiConstants.CPU_SPEED, type = CommandType.INTEGER, required = false, description = "For VMware and Xen based hypervisors this is the CPU speed of the service offering in MHz.\n" +
+            "For the KVM hypervisor," +
+            " the values of the parameters cpuSpeed and cpuNumber will be used to calculate the `shares` value. This value is used by the KVM hypervisor to calculate how much time" +
+            " the VM will have access to the host's CPU. The `shares` value does not have a unit, and its purpose is being a weight value for the host to compare between its guest" +
+            " VMs. For more information, see https://libvirt.org/formatdomain.html#cpu-tuning.")
     private Integer cpuSpeed;
 
     @Parameter(name = ApiConstants.DISPLAY_TEXT, type = CommandType.STRING, description = "The display text of the service offering, defaults to 'name'.")