cxl/Documentation: Add more description about min/max scrub cycle

user can configurare scrub cycle for a region or a memory device via
sysfs interface. Currently, these interfaces have not enough description
for the return value. So adding return value description to these
interfaces.

Suggested-by: Alison Schofield <alison.schofield@intel.com>
Signed-off-by: Shiju Jose <shiju.jose@huawei.com>
Signed-off-by: Li Ming <ming.li@zohomail.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Link: https://patch.msgid.link/20250603104314.25569-2-ming.li@zohomail.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

Author: MingLi-4

Documentation/ABI/testing/sysfs-edac-scrub

@@ -49,6 +49,12 @@ Description:
 		(RO) Supported minimum scrub cycle duration in seconds
 		by the memory scrubber.
 
+		Device-based scrub: returns the minimum scrub cycle
+		supported by the memory device.
+
+		Region-based scrub: returns the max of minimum scrub cycles
+		supported by individual memory devices that back the region.
+
 What:		/sys/bus/edac/devices/<dev-name>/scrubX/max_cycle_duration
 Date:		March 2025
 KernelVersion:	6.15
@@ -57,6 +63,16 @@ Description:
 		(RO) Supported maximum scrub cycle duration in seconds
 		by the memory scrubber.
 
+		Device-based scrub: returns the maximum scrub cycle supported
+		by the memory device.
+
+		Region-based scrub: returns the min of maximum scrub cycles
+		supported by individual memory devices that back the region.
+
+		If the memory device does not provide maximum scrub cycle
+		information, return the maximum supported value of the scrub
+		cycle field.
+
 What:		/sys/bus/edac/devices/<dev-name>/scrubX/current_cycle_duration
 Date:		March 2025
 KernelVersion:	6.15