Document compatibility with Django versions

[mikaeilorfanian]

Hi guys,

I was using this library in my project which also uses Django 1.11 and some errors were thrown. It took me a while to realize that this library is not compatible with the latest versions of Django.
Can you please document this somewhere in your docs? I was looking for this info in your docs and unfortunately, it took me an hour of reading previous pull requests, issues, and Googling around to figure this out.

Thank you.