add version info in Readme

Einstein/Readme.md

@@ -2,7 +2,7 @@
 
 ## ProB2-UI and VisB
 
-You will need to download a recent version of [ProB2-UI](https://www3.hhu.de/stups/prob/index.php/Download#ProB2_UI_using_Java_FX) for the examples below.
+You will need to download a recent version of [ProB2-UI](https://www3.hhu.de/stups/prob/index.php/Download#ProB2_UI_using_Java_FX) for the examples below (1.1.1-SNAPSHOT or newer).
 It will contain the [VisB](https://www3.hhu.de/stups/prob/index.php/VisB) view to allow visualizing states using SVG graphics and simple JSON annotations.