Install tap(4) manpage as vmnet(4) as well

If one comes across a vmnet interface, this is a useful pointer to have
towards what it actually is if they're otherwise unfamiliar.

MFC after:	3 days

share/man/man4/Makefile

@@ -729,7 +729,9 @@ MLINKS+=stf.4 if_stf.4
 MLINKS+=stge.4 if_stge.4
 MLINKS+=syncache.4 syncookies.4
 MLINKS+=syscons.4 sc.4
-MLINKS+=tap.4 if_tap.4
+MLINKS+=tap.4 if_tap.4 \
+	tap.4 vmnet.4 \
+	tap.4 if_vmnet.4
 MLINKS+=tdfx.4 tdfx_linux.4
 MLINKS+=ti.4 if_ti.4
 MLINKS+=tun.4 if_tun.4

share/man/man4/tap.4

@@ -1,11 +1,12 @@
 .\" $FreeBSD$
 .\" Based on PR#2411
 .\"
-.Dd April 29, 2019
+.Dd January 13, 2020
 .Dt TAP 4
 .Os
 .Sh NAME
-.Nm tap
+.Nm tap ,
+.Nm vmnet
 .Nd Ethernet tunnel software network interface
 .Sh SYNOPSIS
 .Cd device tuntap