Fixed #19965 - Added a warning that the tutorial is written for Python 2.

If Django is installed, you should see the version of your installation. If it

isn't, you'll get an error telling "No module named django".

This tutorial is written for Django |version|. If the versions don't match,

you can refer to the tutorial for your version of Django or update Django to

the newest version.

This tutorial is written for Django |version| and Python 2.x. If the Django

version doesn't match, you can refer to the tutorial for your version of Django

or update Django to the newest version. If you are using Python 3.x, be aware

that your code may need to differ from what is in the tutorial and you should

continue using the tutorial only if you know what you are doing with Python

3.x.

See :doc:`How to install Django </topics/install>` for advice on how to remove

older versions of Django and install a newer one.