Update README.md

Author: yorkie

README.md

@@ -13,58 +13,60 @@ feature.
 
 Take the following example server:
 
-    var middleware = require('./middleware');
-
-    var app = middleware.createServer();
-
-    app.use(function (req, res, next) {
-      res.write('a');
-      next();
-    });
-
-    app.use('/hello', function (req, res, next) {
-      res.write('b');
-      next();
-    });
-
-    app.use(function (req, res, next) {
-      res.write('c');
-      next();
-    });
-
-    app.use('/hello', function (req, res) {
-      res.end('hello');
-    });
-
-    app.use('/goodbye', function (req, res) {
-      res.end('goodbye');
-    });
-
-    app.use(function (req, res) {
-      res.end('end');
-    });
-
-    app.listen(3000, function () {
-      console.log('Server started at 3000');
-    });
-
+```js
+var middleware = require('./middleware');
+var app = middleware.createServer();
+
+app.use(function (req, res, next) {
+    res.write('a');
+    next();
+});
+
+app.use('/hello', function (req, res, next) {
+    res.write('b');
+    next();
+});
+
+app.use(function (req, res, next) {
+    res.write('c');
+    next();
+});
+
+app.use('/hello', function (req, res) {
+    res.end('hello');
+});
+
+app.use('/goodbye', function (req, res) {
+    res.end('goodbye');
+});
+
+app.use(function (req, res) {
+    res.end('end');
+});
+
+app.listen(3000, function () {
+    console.log('Server started at 3000');
+});
+```
 
 Your micro-framework will implement at least 3 methods:
 
-* `createServer()`
-* `use(handler)`
-* `listen(port, callback)`
++ `createServer()`
++ `use(handler)`
++ `listen(port, callback)`
 
 The above server will run as you would expect:
 
-* `GET /hello` would return `abchello`
-* `GET /goodbye` would return `acgoodbye`
-* `GET /` would return `acend`
++ `GET /hello` would return `abchello`
++ `GET /goodbye` would return `acgoodbye`
++ `GET /` would return `acend`
 
 Do you have what it takes?
 
 
 ## Usage
 
-    $ npm install
-    $ npm test
+```sh
+$ npm install
+$ npm test
+```