Added Debugger "int" command to manually request interrupts

devices/pc8080/machine/invaders/debugger/README.md

@@ -0,0 +1,27 @@
+---
+layout: page
+title: Space Invaders (1978) with Debugger
+permalink: /devices/pc8080/machine/invaders/debugger/
+machines:
+  - type: pc8080
+    id: invaders
+    debugger: true
+---
+
+Space Invaders (1978) with Debugger
+-----------------------------------
+
+The [PC8080](/modules/pc8080/) machine below is configured to run [Space Invaders](/devices/pc8080/machine/invaders/)
+with a Control Panel and Debugger.  It is currently playable only in desktop browsers and uses the following hard-coded
+key mappings:
+
+- 1: One Player
+- 2: Two Player
+- 3: Insert Coin
+- A: Move Left
+- D: Move Right
+- L: Fire Missile
+
+Click the "Run" button when you're ready to start the simulation. 
+
+{% include machine.html id="invaders" %}