docs: mention CRC32 checksum for add_js_file and add_css_file (7.1)

[Devika9705]

This pull request updates the documentation in doc/extdev/appapi.rst to reflect recent changes introduced in Sphinx 7.1, where app.add_js_file() and app.add_css_file() now automatically include a CRC32 checksum for static files.

Summary of Changes

• Updated the documentation to mention the new CRC32 checksum behavior.
• Clarified how this affects browser caching and file updates for JS and CSS assets.

Why This Matters

Adding the CRC32 checksum ensures that browsers automatically reload updated assets without relying on manual cache clearing, improving developer experience and reliability in extension development.

References

• Related code: sphinx/application.py
• Introduced in: Sphinx 7.1
• Inspired by: discussions in #12223

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Purpose

This PR improves developer-facing documentation by clarifying recent updates to the JavaScript and CSS inclusion APIs (add_js_file and add_css_file).
No code changes are made — this is a documentation-only update.

References

• Related PR: #12223
• Related file: sphinx/application.py

[AA-Turner]

Hi, if using LLMs to create PRs please (a) disclose this fact and (b) ensure that the PR doesn't contain unneeded changes.

Also, here we add the checksum to all asset files, not just via these API calls.

A

[Devika9705]

Hi, if using LLMs to create PRs please (a) disclose this fact and (b) ensure that the PR doesn't contain unneeded changes.

Also, here we add the checksum to all asset files, not just via these API calls.

A

Thank you for your concern. As a beginner learning through LLMs, I will update the PR as you mentioned.