added screenshot

Author: svenefftinge

README.md

@@ -2,6 +2,8 @@
 
 A Javascript framework for native desktop and cloud-based IDEs.
 
+![Theia](https://cloud.githubusercontent.com/assets/372735/25758586/6939d0de-31cf-11e7-998a-e4ce997dd6b8.png)
+
 ## Scope
  - Provide the end-user with a full-fledged multi-language IDE  (not just a smart editor)
  - Support equally the paradigm of Cloud IDE and Desktop IDE