documentation: add Documentation/x86-64/00-INDEX

Signed-off-by: Rob Landley <rob@landley.net>
Cc: Vojtech Pavlik <vojtech@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Documentation/x86_64/00-INDEX

+00-INDEX
+	- This file
+boot-options.txt
+	- AMD64-specific boot options.
+cpu-hotplug-spec
+	- Firmware support for CPU hotplug under Linux/x86-64
+fake-numa-for-cpusets
+	- Using numa=fake and CPUSets for Resource Management
+kernel-stacks
+	- Context-specific per-processor interrupt stacks.
+machinecheck
+	- Configurable sysfs parameters for the x86-64 machine check code.
+mm.txt
+	- Memory layout of x86-64 (4 level page tables, 46 bits physical).
+uefi.txt
+	- Booting Linux via Unified Extensible Firmware Interface.