Clarify the format of the Access-Control-Request-Headers header (#33313)

[jub0bs]

Description

Be more precise about the format of the Access-Control-Request-Headers header.

Motivation

Imprecision can give practitioners false expectations.

Related issues and pull requests

Fixes #33313

[github-actions[bot]]

Preview URLs

• /en-US/docs/Glossary/Preflight_request
• /en-US/docs/Web/HTTP/CORS
• /en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Headers
• /en-US/docs/Web/HTTP/Headers/Access-Control-Request-Headers
• /en-US/docs/Web/HTTP/Methods/OPTIONS

(comment last updated: 2024-04-29 15:54:41)