documentation: move mtrr.txt to Doc/x86/ subdir

Move mtrr.txt to the Documentation/x86/ subdirectory.
Add 00-INDEX to the Documentation/x86/ subdirectory.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Documentation/00-INDEX

@@ -253,8 +253,6 @@ mono.txt
 	- how to execute Mono-based .NET binaries with the help of BINFMT_MISC.
 moxa-smartio
 	- file with info on installing/using Moxa multiport serial driver.
-mtrr.txt
-	- how to use PPro Memory Type Range Registers to increase performance.
 mutex-design.txt
 	- info on the generic mutex subsystem.
 namespaces/

Documentation/x86/00-INDEX

+00-INDEX
+	- this file
+mtrr.txt
+	- how to use x86 Memory Type Range Registers to increase performance

arch/x86/Kconfig

@@ -1131,7 +1131,7 @@ config MTRR
 	  You can safely say Y even if your machine doesn't have MTRRs, you'll
 	  just add about 9 KB to your kernel.
 
-	  See <file:Documentation/mtrr.txt> for more information.
+	  See <file:Documentation/x86/mtrr.txt> for more information.
 
 config MTRR_SANITIZER
 	bool