fix(text/javascript): Clarify charset validity in HTTP vs HTML contex…

[Shrinivassab]

Description

Updated text/javascript MIME type docs to clarify that charset is valid in HTTP headers.

Motivation

Fixes incorrect documentation that claimed charset is always invalid.

Additional details

Related issues and pull requests

Fixes #39505

[github-actions]

Preview URLs

• /en-US/docs/Web/HTTP/Guides/MIME_types

Flaws (3)

URL: /en-US/docs/Web/HTTP/Guides/MIME_types
Title: Media types (MIME types)
Flaw count: 3

• unknown:
  • No generic content config found
  • no blog root
  • no blog root

External URLs (4)

URL: /en-US/docs/Web/HTTP/Guides/MIME_types
Title: Media types (MIME types)

• https://html.spec.whatwg.org/multipage/scripting.html (1 time) (Note! This may be a new URL 👀)
• https://www.iana.org/ (1 time) (Note! This may be a new URL 👀)
• https://www.iana.org/assignments/media-types/media-types.xhtml (11 times) (Note! This may be a new URL 👀)
• https://www.rfc-editor.org/rfc/rfc9239.html (1 time) (Note! This may be a new URL 👀)