ACPI: document method tracing hooks

Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/Documentation/00-INDEX b/Documentation/00-INDEX
index 299615d..161edbc 100644
--- a/Documentation/00-INDEX
+++ b/Documentation/00-INDEX
@@ -14,6 +14,7 @@
 	- this file.
 ABI/
 	- info on kernel <-> userspace ABI and relative interface stability.
+
 BUG-HUNTING
 	- brute force method of doing binary search of patches to find bug.
 Changes
@@ -66,6 +67,8 @@
 	- how to change your VGA cursor from a blinking underscore.
 accounting/
 	- documentation on accounting and taskstats.
+acpi/
+	- info on ACPI-specific hooks in the kernel.
 aoe/
 	- description of AoE (ATA over Ethernet) along with config examples.
 applying-patches.txt