docs(next.config): this docs should remove ".mts" is not supported. (#85716)

Fix #85715

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Co-authored-by: graphite-app[bot] <96075541+graphite-app[bot]@users.noreply.github.com>
Co-authored-by: Jiwon Choi <[email protected]>

Author: 3 people

docs/01-app/03-api-reference/05-config/01-next-config-js/index.mdx

@@ -37,7 +37,7 @@ const nextConfig = {
 export default nextConfig
 ```
 
-> **Good to know**: `next.config` with the `.cjs`, `.cts`, or `.mts` extensions are currently **not** supported.
+> **Good to know**: `next.config` with the `.cjs` or `.cts` extensions are currently **not** supported.
 
 ## Configuration as a Function