remove most of PF_INET6 description. add references only.

Suggested by:	Ruslan Ermilov <ru@FreeBSD.org>

lib/libc/gen/sysctl.3

@@ -514,7 +514,7 @@ This value applies to normal transport protocols, not to ICMP.
 Returns 1 when UDP checksums are being computed and checked.
 Disabling UDP checksums is strongly discouraged.
 .Pp
-For variables net.*.ipsec, please refer to
+For variables net.inet.*.ipsec, please refer to
 .Xr ipsec 4 .
 .El
 .It Li PF_INET6
@@ -522,144 +522,10 @@ Get or set various global information about the IPv6
 .Pq Internet Protocol version 6 .
 The third level name is the protocol.
 The fourth level name is the variable name.
-The currently defined protocols and names are:
-.Bl -column ProtocolXX nd6_useloopbackXX TypeXX ChangeableXX
-.It Pa Protocol	Variable	Type	Changeable
-.It ip6	forwarding	integer	yes
-.It ip6	redirect	integer	yes
-.It ip6	hlim	integer	yes
-.It ip6	maxfragpackets	integer	yes
-.It ip6	accept_rtadv	integer	yes
-.It ip6	keepfaith	integer	yes
-.It ip6	log_interval	integer	yes
-.It ip6	hdrnestlimit	integer	yes
-.It ip6	dad_count	integer	yes
-.It ip6	auto_flowlabel	integer	yes
-.It ip6	defmcasthlim	integer	yes
-.It ip6	gif_hlim	integer	yes
-.It ip6	kame_version	string	no
-.It ip6	use_deprecated	integer	yes
-.It ip6	rr_prune	integer	yes
-.It ip6	mapped_addr	integer	yes
-.It icmp6	rediraccept	integer	yes
-.It icmp6	redirtimeout	integer	yes
-.It icmp6	errratelimit	integer	yes
-.It icmp6	nd6_prune	integer	yes
-.It icmp6	nd6_delay	integer	yes
-.It icmp6	nd6_umaxtries	integer	yes
-.It icmp6	nd6_mmaxtries	integer	yes
-.It icmp6	nd6_useloopback	integer	yes
-.It icmp6	nd6_proxyall	integer	yes
-.El
 .Pp
-The variables are as follows:
-.Bl -tag -width "123456"
-.It Li ip6.forwarding
-Returns 1 when IPv6 forwarding is enabled for the node,
-meaning that the node is acting as a router.
-.It Li ip6.redirect
-Returns 1 when ICMPv6 redirects may be sent by the node.
-This option is ignored unless the node is routing IP packets,
-and should normally be enabled on all systems.
-.It Li ip6.hlim
-The default hop limit value for an IPv6 unicast packet sourced by the node.
-This value applies to all the transport protocols on top of IPv6.
-There are APIs to override the value.
-.\", as documented in
-.\".Xr ip6 4 .
-.It Li ip6.maxfragpackets
-The maximum number of fragmented packets the node will accept.
-0 means that the node will not accept any fragmented packets.
--1 means that the node will accept as many fragmented packets as it receives.
-The flag is provided basically for avoiding possible DoS attacks.
-.It Li ip6.accept_rtadv
-If set to non-zero, the node will accept ICMPv6 router advertisement packets
-and autoconfigures address prefixes and default routers.
-The node must be a host
-.Pq not a router
-for the option to be meaningful.
-.It Li ip6.keepfaith
-If set to non-zero, it enables
-.Dq FAITH
-TCP relay IPv6-to-IPv4 translator code in the kernel.
-Refer
-.Xr faith 4
-and
-.Xr faithd 8
-for detail.
-.It Li ip6.log_interval
-The variable controls amount of logs generated by IPv6 packet
-forwarding engine, by seting interval between log output
-.Pq in seconds .
-.It Li ip6.hdrnestlimit
-The number of IPv6 extension headers permitted on incoming IPv6 packets.
-If set to 0, the node will accept as many extension headers as possible.
-.It Li ip6.dad_count
-The variable cofigures number of IPv6 DAD
-.Pq duplicated address detection
-probe packets.
-The packets will be generated when IPv6 interface addresses are configured.
-.It Li ip6.auto_flowlabel
-On connected transport protocol packets,
-fill IPv6 flowlabel field to help intermediate routers to identify packet flows.
-.It Li ip6.defmcasthlim
-The default hop limit value for an IPv6 multicast packet sourced by the node.
-This value applies to all the transport protocols on top of IPv6.
-There are APIs to override the value.
-.\", as documented in
-.\".Xr ip6 4 .
-.It Li ip6.gif_hlim
-The maximum hop limit value for an IPv6 packet generated by
-.Xr gif 4
-tunnel interface.
-.It Li ip6.kame_version
-The string identifies the version of KAME IPv6 stack implemented in the kernel.
-.It Li ip6.use_deprecated
-The variable controls use of deprecated address, specified in RFC2462 5.5.4.
-.It Li ip6.rr_prune
-The variable specifies interval between IPv6 router renumbering prefix
-babysitting, in seconds.
-.It Li ip6.mapped_addr
-The variable controls use of IPv4 mapped address on AF_INET6 sockets.
-.It Li icmp6.rediraccept
-If set to non-zero, the host will accept ICMPv6 redirect packets.
-Note that IPv6 routers will never accept ICMPv6 redirect packets,
-and the variable is meaningful on IPv6 hosts
-.Pq non-router
-only.
-.It Li icmp6.redirtimeout
-The variable specifies lifetime of routing entries generated by incoming
-ICMPv6 redirect.
-.It Li icmp6.errratelimit
-The variable specifies minimum interval between ICMPv6 error messages,
-in microseconds.
-.It Li icmp6.nd6_prune
-The variable specifies interval between IPv6 neighbor cache babysitting,
-in seconds.
-.It Li icmp6.nd6_delay
-The variable specifies
-.Dv DELAY_FIRST_PROBE_TIME
-timing constant in IPv6 neighbor discovery specification
-.Pq RFC2461 ,
-in seconds.
-.It Li icmp6.nd6_umaxtries
-The variable specifies
-.Dv MAX_UNICAST_SOLICIT
-constant in IPv6 neighbor discovery specification
-.Pq RFC2461 .
-.It Li icmp6.nd6_mmaxtries
-The variable specifies
-.Dv MAX_MULTICAST_SOLICIT
-constant in IPv6 neighbor discovery specification
-.Pq RFC2461 .
-.It Li icmp6.nd6_useloopback
-If set to non-zero, kernel IPv6 stack will use loopback interface for
-local traffic.
-.It Li icmp6.nd6_proxyall
-The variable enables proxy neighbor advertisements.
-.El
-.Pp
-For variables net.*.ipsec6, please refer to
+For variables net.inet6.* please refer to
+.Xr inet6 4 .
+For variables net.inet6.*.ipsec6, please refer to
 .Xr ipsec 4 .
 .El
 .Sh CTL_USER