changed recommended python 3.3 usage

README.md

@@ -47,7 +47,11 @@ The editrights tools is provided as part of git-repo for Microsoft Windows.
 
 ##### Downloading and installing Git and Python #####
 * sudo apt-get install git-core
-* Since our Repo requires Python 3.3, use the following commands to switch between multiple Python versions:
+* Since our Repo requires Python 3.3, we recommend to change the first line of the ~/bin/repo executable to:
+
+    #!/usr/bin/env python3.3
+
+* Alternatively, use the following commands to switch between multiple Python versions:
 
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