Merge pull request #276 from bitinn/readme-update

Mention 2.x alpha in the main readme

README.md

@@ -35,13 +35,22 @@ See Matt Andrews' [isomorphic-fetch](https://github.com/matthew-andrews/isomorph
 
 ## Install
 
+Stable release (`v1.x`)
+
 ```sh
 $ npm install node-fetch --save
 ```
 
+Next release (`v2.x`), currently in alpha
+
+```sh
+$ npm install node-fetch@next --save
+```
 
 ## Usage
 
+Note that documentation below is up-to-date with `v2.x` releases, [see `v1.x` readme](https://github.com/bitinn/node-fetch/tree/v1.6.3) and [upgrade guide](https://github.com/bitinn/node-fetch/blob/master/UPGRADE-GUIDE.md) if you want to find out the difference.
+
 ```javascript
 import fetch from 'node-fetch';
 // or