Update testing.md (#267)

docs/en/testing.md

@@ -164,4 +164,4 @@ mocha test-bundle.js
 
 #### Running in Browser with Karma + karma-webpack
 
-Consult the setup in [vue-loader documentation](http://vuejs.github.io/vue-loader/workflow/testing.html).
+Consult the setup in [vue-loader documentation](http://vue-loader.vuejs.org/en/workflow/testing.html).