docs: arm: generic-counter: Allow creating cross-references for ABI

Now that Documentation/ABI is processed by automarkup, let it
generate cross-references for the corresponding ABI file.

Signed-off-by: Mauro Carvalho Chehab <[e-mail]>
Signed-off-by: Jonathan Corbet <[e-mail]>
Link: https://lore.kernel.org/r/5faafb[e-mail]

Documentation/driver-api/generic-counter.rst

···
 Translates counter data to the standard Counter sysfs interface format
 and vice versa.
 
-Please refer to the ``Documentation/ABI/testing/sysfs-bus-counter`` file
+Please refer to the Documentation/ABI/testing/sysfs-bus-counter file
 for a detailed breakdown of the available Generic Counter interface
 sysfs attributes.
 
···
 Several sysfs attributes are generated by the Generic Counter interface,
 and reside under the ``/sys/bus/counter/devices/counterX`` directory,
 where ``X`` is to the respective counter device id. Please see
-``Documentation/ABI/testing/sysfs-bus-counter`` for detailed information
+Documentation/ABI/testing/sysfs-bus-counter for detailed information
 on each Generic Counter interface sysfs attribute.
 
 Through these sysfs attributes, programs and scripts may interact with