Add missing sysctls entries to man page

Entries added:
- dev.netmap.generic_rings
- dev.netmap.ptnet_vnet_hdr
- dev.netmap.ptnetmap_tx_workers

share/man/man4/netmap.4

@@ -27,7 +27,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd March 2, 2017
+.Dd January 31, 2018
 .Dt NETMAP 4
 .Os
 .Sh NAME
@@ -872,6 +872,8 @@ Controls the use of native or emulated adapter mode.
 1 forces native mode and fails if not available;
 .Pp
 2 forces emulated hence never fails.
+.It Va dev.netmap.generic_rings: 1
+Number of rings used for emulated netmap mode
 .It Va dev.netmap.generic_ringsize: 1024
 Ring size used for emulated netmap mode
 .It Va dev.netmap.generic_mit: 100000
@@ -913,6 +915,10 @@ Batch size used when moving packets across a
 switch.
 Values above 64 generally guarantee good
 performance.
+.It Va dev.netmap.ptnet_vnet_hdr: 1
+Allow ptnet devices to use virtio-net headers
+.It Va dev.netmap.ptnetmap_tx_workers: 1
+Use worker threads for ptnetmap TX processing
 .El
 .Sh SYSTEM CALLS
 .Nm