docs: x86: move two x86-specific files to x86 arch dir

Those two docs belong to the x86 architecture:

   Documentation/Intel-IOMMU.txt -> Documentation/x86/intel-iommu.rst
   Documentation/intel_txt.txt -> Documentation/x86/intel_txt.rst
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/x86/index.rst

@@ -20,6 +20,8 @@ x86-specific Documentation
    mtrr
    pat
    intel_mpx
+   intel-iommu
+   intel_txt
    amd-memory-encryption
    pti
    mds

MAINTAINERS

@@ -8312,7 +8312,7 @@ L:	tboot-devel@lists.sourceforge.net
 W:	http://tboot.sourceforge.net
 T:	hg http://tboot.hg.sourceforge.net:8000/hgroot/tboot/tboot
 S:	Supported
-F:	Documentation/intel_txt.txt
+F:	Documentation/x86/intel_txt.rst
 F:	include/linux/tboot.h
 F:	arch/x86/kernel/tboot.c
 

security/Kconfig

@@ -121,7 +121,7 @@ config INTEL_TXT
 	  See <http://www.intel.com/technology/security/> for more information
 	  about Intel(R) TXT.
 	  See <http://tboot.sourceforge.net> for more information about tboot.
-	  See Documentation/intel_txt.txt for a description of how to enable
+	  See Documentation/x86/intel_txt.rst for a description of how to enable
 	  Intel TXT support in a kernel boot.
 
 	  If you are unsure as to whether this is required, answer N.