docs: updated demo link

Author: JohnnyTheTank

README.md

@@ -2,7 +2,7 @@
 **block grid** library (css & sass) for [twitter bootstrap](https://github.com/twbs/bootstrap) (version 3 & 4), based on the native [zurb foundation feature](http://foundation.zurb.com/sites/docs/v/5.5.3/components/block_grid.html)
 
 ## demo
-[demo on plnkr](http://embed.plnkr.co/qkyOlC/)
+[demo on plnkr](http://plnkr.co/qkyOlC)
 
 ## usage