Add cross references betwen ttys(5) and related drivers

nmdm(4), ucom(4), and uart(4)

PR:		247638
Submitted by:	Pau Amma <pauamma@gundo.com>
Reported by:	0mp
MFC after:	4 weeks
Sponsored by:	Klara Inc.
Event:		July 2020 Bugathon

libexec/getty/ttys.5

@@ -28,7 +28,7 @@
 .\"     from: @(#)ttys.5	8.1 (Berkeley) 6/4/93
 .\" $FreeBSD$
 .\" "
-.Dd August 3, 2018
+.Dd July 11, 2020
 .Dt TTYS 5
 .Os
 .Sh NAME
@@ -162,6 +162,9 @@ ttyv0	"/usr/local/bin/xterm -display :0"	xterm	on window="/usr/local/bin/X :0"
 .Sh SEE ALSO
 .Xr login 1 ,
 .Xr getttyent 3 ,
+.Xr nmdm 4 ,
+.Xr uart 4 ,
+.Xr ucom 4 ,
 .Xr gettytab 5 ,
 .Xr login.conf 5 ,
 .Xr termcap 5 ,

share/man/man4/nmdm.4

@@ -21,7 +21,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd January 23, 2018
+.Dd July 11, 2020
 .Dt NMDM 4
 .Os
 .Sh NAME
@@ -89,7 +89,8 @@ None.
 .Sh SEE ALSO
 .Xr stty 1 ,
 .Xr termios 4 ,
-.Xr tty 4
+.Xr tty 4 ,
+.Xr ttys 5
 .Sh HISTORY
 The
 .Nm

share/man/man4/uart.4

@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd April 26, 2017
+.Dd July 11, 2020
 .Dt UART 4
 .Os
 .Sh NAME
@@ -286,8 +286,10 @@ for callout ports
 corresponding callout initial-state and lock-state devices
 .El
 .Sh SEE ALSO
+.Xr cu 1 ,
 .Xr puc 4 ,
-.Xr scc 4
+.Xr scc 4 ,
+.Xr ttys 5
 .\"
 .Sh HISTORY
 The

share/man/man4/ucom.4

@@ -29,7 +29,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd April 25, 2018
+.Dd July 11, 2020
 .Dt UCOM 4
 .Os
 .Sh NAME
@@ -125,6 +125,7 @@ for callout ports
 corresponding callout initial-state and lock-state devices
 .El
 .Sh SEE ALSO
+.Xr cu 1 ,
 .Xr tty 4 ,
 .Xr uark 4 ,
 .Xr ubsa 4 ,
@@ -144,7 +145,8 @@ corresponding callout initial-state and lock-state devices
 .Xr usb 4 ,
 .Xr uslcom 4 ,
 .Xr uvisor 4 ,
-.Xr uvscom 4
+.Xr uvscom 4 ,
+.Xr ttys 5
 .Sh HISTORY
 The
 .Nm