Polish guide site doesn't exist any more.

Polish guide site (http://blog.plainly.co/initializr-polish-guide/) Does not exist any more.
So link shown below can be updated or deleted.

![image](https://cloud.githubusercontent.com/assets/15805253/20866549/975ce018-ba2f-11e6-886b-4c626986b5f4.png)

Thanks
Artur