pf: Remove references to pflow from the pf.conf man page

pflow no longer exists. It was removed as part of a pf update back in 2012
(r240233).

PR:		223957
MFC after:	1 week

share/man/man5/pf.conf.5

@@ -28,7 +28,7 @@
 .\" ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd October 27, 2018
+.Dd January 5, 2019
 .Dt PF.CONF 5
 .Os
 .Sh NAME
@@ -547,7 +547,7 @@ without an explicit
 .Ar keep state .
 For example:
 .Bd -literal -offset indent
-set state-defaults pflow, no-sync
+set state-defaults no-sync
 .Ed
 .It Ar set hostid
 The 32-bit
@@ -2136,10 +2136,6 @@ easier.
 This is intended to be used in situations where one does not see all
 packets of a connection, e.g. in asymmetric routing situations.
 Cannot be used with modulate or synproxy state.
-.It Ar pflow
-States created by this rule are exported on the
-.Xr pflow 4
-interface.
 .El
 .Pp
 Multiple options can be specified, separated by commas:
@@ -3009,7 +3005,7 @@ tos            = ( "lowdelay" | "throughput" | "reliability" |
                  [ "0x" ] number )
 
 state-opts     = state-opt [ [ "," ] state-opts ]
-state-opt      = ( "max" number | "no-sync" | timeout | "sloppy" | "pflow" |
+state-opt      = ( "max" number | "no-sync" | timeout | "sloppy" |
                  "source-track" [ ( "rule" | "global" ) ] |
                  "max-src-nodes" number | "max-src-states" number |
                  "max-src-conn" number |
@@ -3072,7 +3068,6 @@ Service name database.
 .Xr ip 4 ,
 .Xr ip6 4 ,
 .Xr pf 4 ,
-.Xr pflow 4 ,
 .Xr pfsync 4 ,
 .Xr tcp 4 ,
 .Xr udp 4 ,