ACPI, APEI, Document for APEI

Add document for APEI, including kernel parameters and EINJ debug file
sytem interface.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 839b21b..47a0e1b 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -843,6 +843,11 @@
 	hd=		[EIDE] (E)IDE hard drive subsystem geometry
 			Format: <cyl>,<head>,<sect>
 
+	hest_disable	[ACPI]
+			Disable Hardware Error Source Table (HEST) support;
+			corresponding firmware-first mode error processing
+			logic will be disabled.
+
 	highmem=nn[KMG]	[KNL,BOOT] forces the highmem zone to have an exact
 			size of <nn>. This works even on boxes that have no
 			highmem otherwise. This also works to reduce highmem