Adding clocking mechanism for serial data transmission

devices/pc8080/machine/vt100/dual/README.md

@@ -20,6 +20,8 @@ This is a test of two [VT100 Terminals](../) whose serial ports are *virtually*
 terminal should appear on the screen of the second, and vice versa.  Click or tap on the screen of the desired terminal before
 you begin typing.
 
+A [Dual Debugger Configuration](debugger/) is also available.
+
 If either terminal becomes LOCKED, press the SET-UP key (mapped to your F9 function key) twice to unlock it. 
 
 {% include machine.html id="vt100a" %}