Add binder pic (#9)

Author: Sandra Mierz

Binder.png

@@ -25,6 +25,8 @@ While GitHub renders Jupyter notebooks as static HTML files (not executable),
 you can use this link to launch the notebooks on Binder where you can execute and modify them:
 [![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/Project-TAPIR/pidgraph-notebooks/main)
 
+![Screenshot Binder](Binder.png)
+
 ----------------------------
 
 ### Background