docs: driver-model: move it to the driver-api book

The audience for the Kernel driver-model is clearly Kernel hackers.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> # ice driver changes
diff --git a/Documentation/filesystems/sysfs.txt b/Documentation/filesystems/sysfs.txt
index 5b5311f..ddf15b1 100644
--- a/Documentation/filesystems/sysfs.txt
+++ b/Documentation/filesystems/sysfs.txt
@@ -319,7 +319,7 @@
 a stat(2) operation.
 
 More information can driver-model specific features can be found in
-Documentation/driver-model/. 
+Documentation/driver-api/driver-model/.
 
 
 TODO: Finish this section.