Simplify do.coffee

This version is directly executable, and illustrates more directly the concept. One can comment out line jashkenas#3 and run again to see the difference.

documentation/coffee/do.coffee

@@ -1,4 +1,6 @@
-for filename in list
-  do (filename) ->
-    fs.readFile filename, (err, contents) ->
-      compile filename, contents.toString()
+multipliers = [1, 2, 3]
+multiples = for j in multipliers
+  do (j) ->
+    (x) -> x * j
+
+alert(f(2) for f in multiples)