IMA: update IMA policy documentation to include pcr= option

Commit 0260643c "ima: add policy support for extending different pcrs"
introduced a new IMA policy option "pcr=".  Missing was the documentation
for this option.  This patch updates ima_policy to include this option,
as well as an example.
Signed-off-by: Eric Richter <erichte@linux.vnet.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

Documentation/ABI/testing/ima_policy

@@ -34,9 +34,10 @@ Description:
 			fsuuid:= file system UUID (e.g 8bcbe394-4f13-4144-be8e-5aa9ea2ce2f6)
 			uid:= decimal value
 			euid:= decimal value
-			fowner:=decimal value
+			fowner:= decimal value
 		lsm:  	are LSM specific
 		option:	appraise_type:= [imasig]
+			pcr:= decimal value
 
 		default policy:
 			# PROC_SUPER_MAGIC
@@ -96,3 +97,8 @@ Description:
 
 		Smack:
 			measure subj_user=_ func=FILE_CHECK mask=MAY_READ
+
+		Example of measure rules using alternate PCRs:
+
+			measure func=KEXEC_KERNEL_CHECK pcr=4
+			measure func=KEXEC_INITRAMFS_CHECK pcr=5