debugger: a little bit of doc

doc/api/_toc.markdown

@@ -28,6 +28,7 @@
 * [Assertion Testing](assert.html)
 * [TTY](tty.html)
 * [OS](os.html)
+* [Debugger](debugger.html)
 * Appendixes
   * [Appendix 1: Recommended Third-party Modules](appendix_1.html)
   * [Appendix 2: Deprecated API's](appendix_2.html)

doc/api/all.markdown

@@ -29,6 +29,7 @@
 @include assert
 @include tty
 @include os
+@include debugger
 
 # Appendixes
 @include appendix_1

doc/api/debugger.markdown

@@ -0,0 +1,73 @@
+## Debugger
+
+V8 comes with an extensive debugger which is accessable out-of-process via a
+simple [TCP protocol](http://code.google.com/p/v8/wiki/DebuggerProtocol).
+Node has a built-in client for this debugger. To use this, start Node with the
+`debug` argument; a prompt will appear:
+
+    % node debug myscript.js
+    debug>
+
+At this point `myscript.js` is not yet running. To start the script, enter
+the command `run`. If everything works okay, the output should look like
+this:
+
+    % node debug myscript.js
+    debug> run
+    debugger listening on port 5858
+    connecting...ok
+
+Node's debugger client doesn't support the full range of commands, but
+simple step and inspection is possible. By putting the statement `debugger;`
+into the source code of your script, you will enable a breakpoint.
+
+For example, suppose `myscript.js` looked like this:
+
+    // myscript.js
+    x = 5;
+    setTimeout(function () {
+      debugger;
+      console.log("world");
+    }, 1000);
+    console.log("hello");
+
+Then once the debugger is run, it will break on line 4.
+
+    % ./node debug myscript.js
+    debug> run
+    debugger listening on port 5858
+    connecting...ok
+    hello
+    break in #<an Object>._onTimeout(), myscript.js:4
+      debugger;
+      ^
+    debug> next
+    break in #<an Object>._onTimeout(), myscript.js:5
+      console.log("world");
+      ^
+    debug> print x
+    5
+    debug> print 2+2
+    4
+    debug> next
+    world
+    break in #<an Object>._onTimeout() returning undefined, myscript.js:6
+    }, 1000);
+    ^
+    debug> quit
+    A debugging session is active. Quit anyway? (y or n) y
+    %
+
+
+The `print` command allows you to evaluate variables. The `next` command steps
+over to the next line. There are a few other commands available and more to
+come type `help` to see others.
+
+
+### Advanced Usage
+
+The V8 debugger can be enabled and accessed either by starting Node with
+the `--debug` command-line flag or by signaling an existing Node process
+with `SIGUSR1`.
+
+