vt.4: explain console fonts

Add explaination about console fonts, how to convert them, which subset
of things support them and how to use them.

Reviewed by: imp
Pull Request: https://github.com/freebsd/freebsd-src/pull/1063

share/man/man4/vt.4

@@ -47,6 +47,7 @@ In
 .Cd kern.vt.color.<colornum>.rgb="<colorspec>"
 .Cd kern.vt.fb.default_mode="<X>x<Y>"
 .Cd kern.vt.fb.modes.<connector>="<X>x<Y>"
+.Cd screen.font="<X>x<Y>"
 .Pp
 In
 .Xr loader.conf 5 or
@@ -257,6 +258,11 @@ It will contain a list of connectors and their associated tunables.
 This is currently only supported by the
 .Cm vt_fb
 backend when it is paired with a KMS video driver.
+.It Va screen.font
+Set this value to the base name of the desired font file located in
+.Pa /boot/fonts .
+Fonts can be converted for use with
+.Xr vtfontcvt 8 .
 .El
 .Sh KEYBOARD SYSCTL TUNABLES
 These settings control whether certain special key combinations are enabled or
@@ -358,6 +364,14 @@ To set black and white colors of console palette
 .Pp
 .Dl kern.vt.color.0.rgb="10,10,10"
 .Dl kern.vt.color.15.rgb="#f0f0f0"
+.Pp
+Load the 8x16 font in
+.Xr loader.conf 5
+from
+.Pa /boot/fonts/*.fnt[.gz]
+at boot:
+.Pp
+.Dl screen.font="8x16"
 .Sh SEE ALSO
 .Xr kbdcontrol 1 ,
 .Xr login 1 ,
@@ -371,6 +385,7 @@ To set black and white colors of console palette
 .Xr syscons 4 ,
 .Xr ukbd 4 ,
 .Xr kbdmap 5 ,
+.Xr loader.conf 5 ,
 .Xr rc.conf 5 ,
 .Xr ttys 5 ,
 .Xr config 8 ,