cpufreq: docs: Add missing scaling_available_frequencies description

Add a description of the scaling_available_frequencies attribute in
sysfs to the documentation.

Signed-off-by: Raphael Gallais-Pou <[email protected]>
Reviewed-by: Bagas Sanjaya <[email protected]>
Acked-by: Viresh Kumar <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Rafael J. Wysocki <[email protected]>

Author: GallaisPoutine

Documentation/admin-guide/pm/cpufreq.rst

@@ -267,6 +267,10 @@ are the following:
 ``related_cpus``
 	List of all (online and offline) CPUs belonging to this policy.
 
+``scaling_available_frequencies``
+	List of available frequencies of the CPUs belonging to this policy
+	(in kHz).
+
 ``scaling_available_governors``
 	List of ``CPUFreq`` scaling governors present in the kernel that can
 	be attached to this policy or (if the |intel_pstate| scaling driver is