web/wasm: note that changing HTTP headers is now only recommended, not required for Wasm

[kevmoo]

Page URL

https://docs.flutter.dev/platform-integration/web/wasm#serve-the-built-output-with-an-http-server

Page source

https://github.com/flutter/website/tree/main/src/content/platform-integration/web/wasm.md

Describe the problem

Flutter 3.29 now allows Wasm to run on hosts without changing HTTP response headers.

Performance is improved when using the correct headers as it allows multi-threaded rendering, but users should still see improvements over JS even without header changes.

Expected fix

Update wording to be clear about the above changes in Flutter 3.29

Additional context

Make sure to mention the version.

I would like to fix this problem.

• I will try and fix this problem on docs.flutter.dev.