[NET]: Update some sysctl documentation.

I ran the following (crappy) script:
 ...
In /proc/sys/ and found a host of undocumented sysctls. This patch documents
a number of them, and at least mentions the rest as 'TODO'. Please verify my
code-inspired documentation before applying!
Signed-off-by: Bert Hubert <ahu@ds9a.nl>
Signed-off-by: David S. Miller <davem@redhat.com>

Documentation/filesystems/proc.txt

@@ -1640,7 +1640,8 @@ flush
 
 Writing to this file results in a flush of the routing cache.
 
-gc_elastic, gc_interval, gc_min_interval, gc_tresh, gc_timeout
+gc_elasticity, gc_interval, gc_min_interval, gc_tresh, gc_timeout,
+gc_thresh, gc_thresh1, gc_thresh2, gc_thresh3
 --------------------------------------------------------------
 
 Values to  control  the  frequency  and  behavior  of  the  garbage collection

Documentation/networking/ip-sysctl.txt

@@ -17,6 +17,16 @@ ip_no_pmtu_disc - BOOLEAN
 	Disable Path MTU Discovery.
 	default FALSE
 
+min_pmtu - INTEGER
+	default 562 - minimum discovered Path MTU
+
+mtu_expires - INTEGER
+	Time, in seconds, that cached PMTU information is kept.
+
+min_adv_mss - INTEGER
+	The advertised MSS depends on the first hop route MTU, but will
+	never be lower than this setting.
+
 IP Fragmentation:
 
 ipfrag_high_thresh - INTEGER
@@ -345,6 +355,19 @@ tcp_default_win_scale - INTEGER
 	conections.
 	Default: 7
 
+
+tcp_frto - BOOLEAN
+	Enables F-RTO, an enhanced recovery algorithm for TCP retransmission
+	timeouts.  It is particularly beneficial in wireless environments
+	where packet loss is typically due to random radio interference
+	rather than intermediate router congestion.
+
+somaxconn - INTEGER
+	Limit of TCP listen backlog, known in userspace as SOMAXCONN.
+	Defaults to 128
+
+IP Variables:
+
 ip_local_port_range - 2 INTEGERS
 	Defines the local port range that is used by TCP and UDP to
 	choose the local port. The first number is the first, the 
@@ -586,6 +609,19 @@ arp_ignore - INTEGER
 	The max value from conf/{all,interface}/arp_ignore is used
 	when ARP request is received on the {interface}
 
+app_solicit - INTEGER
+	The maximum number of probes to send to the user space ARP daemon
+	via netlink before dropping back to multicast probes (see
+	mcast_solicit).  Defaults to 0.
+
+disable_policy - BOOLEAN
+	Disable IPSEC policy (SPD) for this interface
+
+disable_xfrm - BOOLEAN
+	Disable IPSEC encryption on this interface, whatever the policy
+
+
+
 tag - INTEGER
 	Allows you to write a number, which can be used as required.
 	Default value is 0.
@@ -804,4 +840,25 @@ bridge-nf-filter-vlan-tagged - BOOLEAN
 	Default: 1
 
 
+UNDOCUMENTED:
+
+dev_weight FIXME
+discovery_slots FIXME
+discovery_timeout FIXME
+fast_poll_increase FIXME
+ip6_queue_maxlen FIXME
+lap_keepalive_time FIXME
+lo_cong FIXME
+max_baud_rate FIXME
+max_dgram_qlen FIXME
+max_noreply_time FIXME
+max_tx_data_size FIXME
+max_tx_window FIXME
+min_tx_turn_time FIXME
+mod_cong FIXME
+no_cong FIXME
+no_cong_thresh FIXME
+slot_timeout FIXME
+warn_noreply_time FIXME
+
 $Id: ip-sysctl.txt,v 1.20 2001/12/13 09:00:18 davem Exp $