nfs: fix out-of-date connectathon talk URL

Reported-by: David Wysochanski <dwysocha@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

net/sunrpc/svc_xprt.c

@@ -35,7 +35,7 @@ static void svc_delete_xprt(struct svc_xprt *xprt);
 /* apparently the "standard" is that clients close
  * idle connections after 5 minutes, servers after
  * 6 minutes
- *   http://www.connectathon.org/talks96/nfstcp.pdf
+ *   http://nfsv4bat.org/Documents/ConnectAThon/1996/nfstcp.pdf
  */
 static int svc_conn_age_period = 6*60;