Oops :(
Improved docs for `contrib.admin.options.ModelAdmin.response_*`

Added links to code references in the docs for `response_add`,
`response_change` and `response_delete`.
Merge pull request #1592 from pablomouzo/fix-admin-view-response-methods-docs

Improved docs for `contrib.admin.options.ModelAdmin.response_*`
Fixed #20530 -- Properly decoded non-ASCII query strings on Python 3.

Thanks mitsuhiko for the report.

This commit just adds a test since the problem was fixed in 8aaca651.
Fixed #20938 -- Added cached sessions note to deployment checklist.

Thanks mjtamlyn for the suggestion.
Fixed #20836 -- Ensure that the ForeignKey's to_field attribute is properly considered by the admin's interface when creating related objects.
Many thanks to Collin Anderson for the report and patch and to Peter Sheats for the test.
Fixed #20876 -- Changed Poll class name for Question class.

Replace the image admin06.png.
Merge branch 'master' of https://github.com/django/django
Merge branch 'ticket_19298'

Conflicts:
	docs/intro/_images/admin06.png
	docs/intro/_images/admin06t.png