comment on python-venv

Author: jpcottin

README.md

@@ -13,7 +13,7 @@ Please file issues if you notice that anything is not working as expected.
 These demos are intended to be run on a linux OS. Your system must meet the
 following requirements:
 
-- A Python interpreter must be installed.
+- A Python interpreter must be installed (python3 with python3-venv to create virtual environments) 
 - ADB must be available on the path. ADB comes as part of th Android SDK.
   Note that installing the command line tools is sufficient.
 - [Docker](https://docs.docker.com/v17.12/install/) must be installed. Make