Document examples for all view decorators

[Adam Johnson]

​This documentation section does not give examples of using each decorator, which makes it much harder to understand. Let’s add one example per decorator.

[Sarah Boyce]

require_GET/POST/safe is probably fine as there is an example for require_http_methods

Conditional view processing has a topic with examples: ​https://docs.djangoproject.com/en/dev/topics/conditional-view-processing/
Vary headers has a topic with examples: ​https://docs.djangoproject.com/en/dev/topics/cache/#using-vary-headers
Cache control is within the cache topic with examples: ​https://docs.djangoproject.com/en/dev/topics/cache/#controlling-cache-using-other-headers
Append slash has an example with the linked middleware: ​https://docs.djangoproject.com/en/dev/ref/middleware/#django.middleware.common.CommonMiddleware

GZip compression has no example and doesn't link to the middleware (when I think it should): ​https://docs.djangoproject.com/en/dev/ref/middleware/#module-django.middleware.gzip

So I think it's roughly there but in different places.
Do you think the examples should be duplicated? Moved over? Or just more prominent links to the topics?