Unused hyperlink targets in the docs point to nonexistent pages

[Max Azatian]

Nine named hyperlink targets in the docs are never referenced, and each one points at a URL that doesn't exist on docs.djangoproject.com. They are leftovers from an older docs layout, e.g. .. _forms documentation: ../forms/ in docs/howto/custom-model-fields.txt resolves to ​https://docs.djangoproject.com/en/dev/howto/forms/, which is a 404.

The targets, on main at 4fab678:

• docs/howto/custom-model-fields.txt: helper functions (../forms/#generating-forms-for-models) and forms documentation (../forms/)
• docs/ref/contrib/sitemaps.txt: URLconf (../url_dispatch/)
• docs/ref/templates/language.txt: The Django template language: For Python programmers (../templates_python/)
• docs/topics/i18n/translation.txt: settings file (../settings/), middleware documentation (../middleware/), session (../sessions/) and request object (../request_response/#httprequest-objects)
• docs/topics/settings.txt: django-admin (../django-admin/)

None of them is used as name_ or `name`_ anywhere in its file, and docutils only resolves named references within the same document, so removing them changes no rendered output. Each URL above, resolved against its page's published address, returns 404.

Suggested fix: delete the nine targets (13 lines including adjacent blank lines).