docs: admin-guide: Move Dell RBU document from driver-api

This document describes how an admin can use the dell_rbu driver, rather
than any in-kernel API details.
Signed-off-by: NJonathan Neuschäfer <j.neuschaefer@gmx.net>
Acked-by: NAndy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/admin-guide/index.rst

@@ -72,6 +72,7 @@ configure specific aspects of kernel behavior to your liking.
    clearing-warn-once
    cpu-load
    cputopology
+   dell_rbu
    device-mapper/index
    efi-stub
    ext4

Documentation/driver-api/index.rst

@@ -73,7 +73,6 @@ available subsections can be seen below.
    connector
    console
    dcdbas
-   dell_rbu
    edid
    eisa
    ipmb

drivers/platform/x86/Kconfig

@@ -259,7 +259,7 @@ config DELL_RBU
 	 DELL system. Note you need a Dell OpenManage or Dell Update package (DUP)
 	 supporting application to communicate with the BIOS regarding the new
 	 image for the image update to take effect.
-	 See <file:Documentation/driver-api/dell_rbu.rst> for more details on the driver.
+	 See <file:Documentation/admin-guide/dell_rbu.rst> for more details on the driver.
 
 
 config FUJITSU_LAPTOP

drivers/platform/x86/dell_rbu.c

@@ -24,7 +24,7 @@
  * on every time the packet data is written. This driver requires an
  * application to break the BIOS image in to fixed sized packet chunks.
  *
- * See Documentation/driver-api/dell_rbu.rst for more info.
+ * See Documentation/admin-guide/dell_rbu.rst for more info.
  */
 #include <linux/init.h>
 #include <linux/module.h>