opentelemetry-instrumentation-django: improve docs for response_hook with examples of providing attributes from middlewares

[piotrjez]

Description

Suggested documentation updates:

1. Explicitly mention that Django’s middleware stack executes after the request_hook runs,
   so attributes like request.user or request.site are unavailable there.
2. Add examples for AuthenticationMiddleware and CurrentSiteMiddleware showing how to capture
   enduser.id, enduser.username, site.id and site.domain in response_hook.
3. Clarify that this pattern also applies to any custom middleware attaching data to the request object.
4. Update links for Django docs to latest LTS version 5.2

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

1. Virtualenv in Python 3.11
2. tox -e docs
3. Check local build in docs/_build/html/instrumentation/*

Does This PR Require a Core Repo Change?

• Yes. - Link to PR:
• No.

Checklist:

See contributing.md for styleguide, changelog guidelines, and more.

• Followed the style guidelines of this project
• Changelogs have been updated
• Unit tests have been added
• Documentation has been updated

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: xrmx / name: Riccardo Magliocchetti (3ba09be)

[tammy-baylis-swi]

Thanks for updates, lgtm