docs: update babel setup

closes #783

Readme.md

@@ -119,22 +119,21 @@ app.use(convert(function *(next) {
 ```
 
 ## Babel setup
-For Node 4.0 and Babel 6.0 you can setup like this
+
+For Node 4.0 and Babel 6.0 you can setup like this:
 
 ```bash
-// install babel and required presets
-$ npm install babel-core --save
-$ npm install babel-preset-es2015-node5 --save
-$ npm install babel-preset-stage-3 --save
+$ npm install babel-register transform-async-to-generator --save
 ```
 
 ```js
 // set babel in entry file
-require('babel-core/register')({
-  presets: ['es2015-node5', 'stage-3']
+require('babel-register')({
+  plugins: ['transform-async-to-generator']
 });
 ```
 
+Check out an example in koa's [test](test/babel/index.js).
 
 ## Running tests
 

package.json

@@ -47,9 +47,9 @@
     "tag": "next"
   },
   "devDependencies": {
-    "babel-core": "^6.1.2",
     "babel-eslint": "^6.0.0",
     "babel-plugin-transform-async-to-generator": "^6.0.14",
+    "babel-register": "^6.9.0",
     "eslint": "^2.5.3",
     "eslint-config-standard": "^5.1.0",
     "eslint-plugin-babel": "^3.1.0",

test/babel/.babelrc

@@ -1,3 +0,0 @@
-{
-  "plugins": ["transform-async-to-generator"]
-}

test/babel/index.js

@@ -2,5 +2,7 @@
 
 // http://babeljs.io/docs/setup/#babel_register
 
-require('babel-core/register');
+require('babel-register')({
+  plugins: ['transform-async-to-generator']
+});
 require('./_test.js');