Add isp.4 man page.

approved:jkh

share/man/man4/Makefile

@@ -6,7 +6,7 @@ MAN4=	ahc.4 amd.4 amr.4 an.4 ata.4 atkbd.4 atkbdc.4 aue.4 blackhole.4 \
 	divert.4 dummynet.4 faith.4 fd.4 fdc.4 fpa.4 fxp.4 \
 	gif.4 gusc.4 \
 	icmp.4 ifmib.4 iic.4 iicbb.4 iicbus.4 iicsmb.4 \
-	inet.4 inet6.4 intpm.4 intro.4 ip.4 ipfirewall.4 ipsec.4 \
+	inet.4 inet6.4 intpm.4 intro.4 ip.4 ipfirewall.4 ipsec.4 isp.4 \
 	kame.4 keyboard.4 kld.4 \
 	kue.4 lo.4 lp.4 lpbb.4 lpt.4 mem.4 mlx.4 mouse.4 mtio.4 natm.4 \
 	ncr.4 netintro.4 null.4 ohci.4 pass.4 pci.4 pcm.4 pcvt.4 \