Added .env.template

Author: PierreRaybaut

.env .env.template.env renamed to .env.template

@@ -93,9 +93,15 @@ development environment. The easiest way to do this is to use `virtualenv
 <http://pypi.python.org/pypi/virtualenv>`_ and `pip
 <http://pypi.python.org/pypi/pip>`_.
 
-Some environment variables are required to be set before using the project from
-within Visual Studio Code (used in `launch.json` and `tasks.json`). These are:
+Some parameters are required to be set before using the project from within
+Visual Studio Code (used in `launch.json` and `tasks.json`). These are:
 
 * ``PPSTACK_PYTHONEXE``: The path to the Python interpreter to use. This is
   used to launch the application from within Visual Studio Code. If not set,
   the default Python interpreter will be used.
+
+* `.env` file: This file is used to set environment variables for the
+  application. It is used to set the ``PYTHONPATH`` environment variable to
+  the root of the project. This is required to be able to import the project
+  modules from within Visual Studio Code. To create this file, copy the
+  ``.env.template`` file to ``.env`` (and eventually add your own paths).