hwmon: Clarify scope of attribute access

Hardware monitoring sysfs attributes are used and displayed by unrestricted
userspace applications. Standard attributes therefore have to be world
readable, since otherwise those userspace applications would either have
to run as super-user or display an error. None of those makes sense.
Clarify the expected scope of attribute access in the ABI document.

Cc: Naveen Krishna Chatradhi <nchatrad@amd.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/sysfs-interface.rst

@@ -65,6 +65,14 @@ the desired value must be written, note that strings which are not a number
 are interpreted as 0! For more on how written strings are interpreted see the
 "sysfs attribute writes interpretation" section at the end of this file.
 
+Attribute access
+----------------
+
+Hardware monitoring sysfs attributes are displayed by unrestricted userspace
+applications. For this reason, all standard ABI attributes shall be world
+readable. Writeable standard ABI attributes shall be writeable only for
+privileged users.
+
 -------------------------------------------------------------------------
 
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