languages: Add `.mdc` as a recognized Markdown file suffix (#50074)
Avi Fenesh
created
Highlight files ending in `.mdc` as Markdown.
The `.mdc` extension is used by Cursor for its Markdown-based rule files
(`.cursor/rules/*.mdc`). These files are standard Markdown with optional
YAML frontmatter, which the existing Markdown grammar already handles
well. Adding `.mdc` to the recognized suffixes ensures proper syntax
highlighting out of the box.
This was requested during review of the agnix extension PR
([zed-industries/extensions#4743](https://github.com/zed-industries/extensions/pull/4743))
by @MrSubidubi as the preferred approach over defining a custom MDC
language in an extension.
Release Notes:
- Added `.mdc` as a recognized Markdown file extension.