doc: update docbook annotations for socket and skb

The skbuff and sock structure both had missing parameter annotation
values.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/sock.h b/include/net/sock.h
index ebf75db..73c6b00 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -252,6 +252,7 @@
   *	@sk_pacing_rate: Pacing rate (if supported by transport/packet scheduler)
   *	@sk_max_pacing_rate: Maximum pacing rate (%SO_MAX_PACING_RATE)
   *	@sk_sndbuf: size of send buffer in bytes
+  *	@sk_padding: unused element for alignment
   *	@sk_no_check_tx: %SO_NO_CHECK setting, set checksum in TX packets
   *	@sk_no_check_rx: allow zero checksum in RX packets
   *	@sk_route_caps: route capabilities (e.g. %NETIF_F_TSO)
@@ -302,7 +303,8 @@
   *	@sk_backlog_rcv: callback to process the backlog
   *	@sk_destruct: called at sock freeing time, i.e. when all refcnt == 0
   *	@sk_reuseport_cb: reuseport group container
- */
+  *	@sk_rcu: used during RCU grace period
+  */
 struct sock {
 	/*
 	 * Now struct inet_timewait_sock also uses sock_common, so please just