update README file

README.md

@@ -13,9 +13,21 @@ Find it on npm: <http://search.npmjs.org/#/node-sass>
 ## Usage
 
     var sass = require('node-sass');
+    sass.render(scss_content, callback [, options]);
+
+Especially, the options argument is optional. It support two attribute: `include_paths` and `output_style`, both of them are optional.
+
+`include_paths` is an `Array`, you can add a sass import path.
+
+`output_style` is a `String`, its value should be one of `'nested', 'expanded', 'compact', 'compressed'`.
+[Important: currently the argument `output_style` has some problem which may cause the output css becomes nothing because of the libsass, so you should not use it now!]
+
+Here is an example:
+
+    var sass = require('node-sass');
     sass.render('body{background:blue; a{color:black;}}', function(err, css){
       console.log(css)
-    });
+    }/*, { include_paths: [ 'lib/', 'mod/' ], output_style: 'compressed' }*/);
 
 ## Connect/Express middleware
 

binding.cpp

@@ -54,8 +54,8 @@ Handle<Value> Render(const Arguments& args) {
     strcpy(ctx->source_string, *astr);
     ctx->options.include_paths = new char[strlen(*bstr)+1];
     strcpy(ctx->options.include_paths, *bstr);
-    // ctx->options.output_style = args[3]->Int32Value();
-    ctx->options.output_style = SASS_STYLE_NESTED;
+    // ctx->options.output_style = SASS_STYLE_NESTED;
+    ctx->options.output_style = args[3]->Int32Value();
     ctx->callback = Persistent<Function>::New(callback);
     ctx->request.data = ctx;