net: Documentation: RFC 2553bis is now RFC 3493

Signed-off-by: Geoffrey Thomas <geofft@mit.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index db2a406..8154699 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -992,7 +992,7 @@
 		TRUE: disable IPv4-mapped address feature
 		FALSE: enable IPv4-mapped address feature
 
-	Default: FALSE (as specified in RFC2553bis)
+	Default: FALSE (as specified in RFC3493)
 
 IPv6 Fragmentation: