Add @malyw 's guide to upgrade babel

README.md

@@ -13,6 +13,7 @@ npm install babel-loader babel-core babel-preset-es2015 --save-dev
 
 __Note:__ [npm](https://npmjs.com) will deprecate [auto-installing of peerDependencies](https://github.com/npm/npm/issues/6565) on the next major release, so required peer dependencies like babel-core and webpack will have to be listed explicitly in your `package.json`.
 
+__Note:__ If you're upgrading from babel 5 to babel 6, please take a look [at this guide](https://medium.com/@malyw/how-to-update-babel-5-x-6-x-d828c230ec53#.yqxukuzdk).
 
 ## Usage