poster update

README.md

@@ -1,7 +1,7 @@
 ####Welcome
 Calm is an alternative client for [twister](http://twister.net.co/) based on  [original](https://github.com/miguelfreitas/twister-html) with new design, features and bugfixes.
 
-![twister](https://raw.github.com/iHedgehog/twister-calm/master/img/screenshot.jpg)
+![twister](https://raw.github.com/iHedgehog/twister-calm/master/img/poster.jpg)
 
 ####For newbies
 - delete default html folder