docs: fix broken documentation links

Mostly due to x86 and acpi conversion, several documentation
links are still pointing to the old file. Fix them.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Reviewed-by: Wolfram Sang <wsa@the-dreams.de>
Reviewed-by: Sven Van Asbroeck <TheSven73@gmail.com>
Reviewed-by: Bhupesh Sharma <bhsharma@redhat.com>
Acked-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 8869742..0f22026 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1263,7 +1263,7 @@
 	  uniprocessor machines. On a uniprocessor machine, the kernel
 	  will run faster if you say N here.
 
-	  See also <file:Documentation/x86/i386/IO-APIC.txt>,
+	  See also <file:Documentation/x86/i386/IO-APIC.rst>,
 	  <file:Documentation/lockup-watchdogs.txt> and the SMP-HOWTO available at
 	  <http://tldp.org/HOWTO/SMP-HOWTO.html>.