Documentation: gpio: Move drivers-on-gpio.txt to driver-api

Move gpio/drivers-on-gpio.txt to driver-api/gpio/drivers-on-gpio.rst and
make sure it builds cleanly as ReST.
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/gpio/drivers-on-gpio.txt → Documentation/driver-api/gpio/drivers-on-gpio.rst

+============================
 Subsystem drivers using GPIO
 ============================
 

Documentation/driver-api/gpio/index.rst

@@ -11,6 +11,7 @@ Contents:
    driver
    consumer
    board
+   drivers-on-gpio
    legacy
 
 Core

Documentation/gpio/00-INDEX

 00-INDEX
 	- This file
-drivers-on-gpio.txt:
-	- Drivers in other subsystems that can use GPIO to provide more
-	  complex functionality.
 sysfs.txt
 	- Information about the GPIO sysfs interface

Documentation/gpio/sysfs.txt

@@ -32,9 +32,8 @@ standard kernels won't know about. And for some tasks, simple userspace
 GPIO drivers could be all that the system really needs.
 
 DO NOT ABUSE SYSFS TO CONTROL HARDWARE THAT HAS PROPER KERNEL DRIVERS.
-PLEASE READ THE DOCUMENT NAMED "drivers-on-gpio.txt" IN THIS DOCUMENTATION
-DIRECTORY TO AVOID REINVENTING KERNEL WHEELS IN USERSPACE. I MEAN IT.
-REALLY.
+PLEASE READ THE DOCUMENT AT Documentation/driver-api/gpio/drivers-on-gpio.rst
+TO AVOID REINVENTING KERNEL WHEELS IN USERSPACE. I MEAN IT. REALLY.
 
 Paths in Sysfs
 --------------