Fix URLs to always have link text

While the `man` command shows link text if none is specified, pandoc
does not.

doc/sopwith-mission.5

@@ -5,11 +5,11 @@
 .
 .SH DESCRIPTION
 The Sopwith mission format allows \fBsopwith\fR(6) to load custom user-defined
-levels and other modifications to the game. The files use Yocton as their
-basic format:
-.PP
+levels and other modifications to the game. The files use
 .UR https://github.com/fragglet/yocton
+Yocton
 .UE
+as their basic format.
 .PP
 Each \.sop file can contain three different sections:
 .TP

doc/sopwith.6

@@ -264,6 +264,7 @@ continually-active dedicated server is left as an exercise for the reader.
 .\" end no-emscripten
 .SH WWW
 .UR https://fragglet.github.io/sdl-sopwith
+https://fragglet.github.io/sdl-sopwith
 .UE
 .SH BUGS
 .IP \(bu
@@ -280,7 +281,9 @@ does very stupid things.
 There is only one level.
 .SH BUG REPORTS
 Bugs can be reported to the GitHub issue tracker:
+.PP
 .UR https://github.com/fragglet/sdl-sopwith
+https://github.com/fragglet/sdl-sopwith
 .UE
 .
 .SH SEE ALSO

doc/sopwith.cfg.5

@@ -105,10 +105,9 @@ The following settings determine the in-game controls. These are keyboard
 scancodes, so the key binding does not change with keyboard layout. However,
 the name for the key as shown in the in-game options menu should match the
 current keyboard layout.
-The values for these settings are scancodes from the USB standard for HID
-devices:
-.PP
+The values for these settings are scancodes from
 .UR https://www.usb.org/sites/default/files/documents/hut1_12v2.pdf
+the USB standard for HID devices.
 .UE
 .TP
 \fBkey_accelerate\fR