update docs with help on using contrib modules
update docs with help on using contrib modules

This may seem obvious to some but took me awhile to figure out that the easy-thumbnails wasn't self-contained and that I had to pip install easy-thumbnails for it to work. I imagine others will assume the modules themselves are bundled in the contrib.
akx/django-jinja,akx/django-jinja,glogiotatidis/django-jinja,glogiotatidis/django-jinja,niwinz/django-jinja,akx/django-jinja,glogiotatidis/django-jinja,akx/django-jinja,glogiotatidis/django-jinja,niwinz/django-jinja,niwinz/django-jinja