u3g.4: increase visibility + tag spdx

+ add `cellular modem` to document description for apropos
+ s/adapters/cellular modems/ in hardware for release hardware notes
+ massage introductory sentance in description for 4G and PCIe

MFC after:	3 days
Reported by:	Jared Trout <[email protected]> (cellular in title)

share/man/man4/u3g.4

@@ -1,3 +1,5 @@
+.\"-
+.\" SPDX-License-Identifier: ISC
 .\"
 .\" Copyright (c) 2008 AnyWi Technologies
 .\" All rights reserved.
@@ -21,7 +23,7 @@
 .Os
 .Sh NAME
 .Nm u3g
-.Nd USB support for 3G and 4G datacards
+.Nd USB support for 3G and 4G cellular modem datacards
 .Sh SYNOPSIS
 To compile this driver into the kernel,
 place the following lines in your
@@ -45,7 +47,7 @@ by devd(8) when the device is connected.
 The
 .Nm
 driver provides support for the multiple USB-to-serial interfaces exposed by
-many 3G USB/PCCard modems.
+many 3G and 4G USB/PCCard/PCIe modems.
 .Pp
 The device is accessed through the
 .Xr ucom 4
@@ -54,7 +56,7 @@ driver which makes it behave like a
 .Sh HARDWARE
 The
 .Nm
-driver supports the following adapters:
+driver supports the following cellular modems:
 .Pp
 .Bl -bullet -compact
 .It