Upgrade and clarify Django quickstart docs

[bartsanchez]

Hello!

Django latest release is 5.0. After 4.2 the way of configuring compression and caching content has changed, as you are already commenting on the specific Django section ( https://github.com/evansd/whitenoise/blob/main/docs/django.rst ). I've updated also the quickstart by first mentioning the new style but also referring to search for more information for older versions, since I felt it could be misleading like it is now.

I hope you find it useful. Thanks.