[IPV6]: ADDRCONF: Add accept_ra_pinfo sysctl.

This controls whether we accept Prefix Information in RAs.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 8001faa7..404afac 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -723,6 +723,12 @@
 	Functional default: enabled if accept_ra is enabled.
 			    disabled if accept_ra is disabled.
 
+accept_ra_pinfo - BOOLEAN
+	Learn Prefix Inforamtion in Router Advertisement.
+
+	Functional default: enabled if accept_ra is enabled.
+			    disabled if accept_ra is disabled.
+
 accept_redirects - BOOLEAN
 	Accept Redirects.
 
@@ -733,8 +739,8 @@
 	Autoconfigure addresses using Prefix Information in Router 
 	Advertisements.
 
-	Functional default: enabled if accept_ra is enabled.
-			    disabled if accept_ra is disabled.
+	Functional default: enabled if accept_ra_pinfo is enabled.
+			    disabled if accept_ra_pinfo is disabled.
 
 dad_transmits - INTEGER
 	The amount of Duplicate Address Detection probes to send.