Detect vscode-specific JSONC files about linguist

[lildude]

This has been attempted before many times and it's not trivial to implement because the filenames are generic with nothing that can be relied upon to 100% correctly identify the file in isolation should be JSONC.

You can see the closed attempts https://github.com/github-linguist/linguist/pulls?q=is%3Apr+jsonc+is%3Aclosed+

Have a read through them to see the challenges we face.

I'm going to close this as not planned as this has been investigated before and there isn't a reliable way of doing this.

You can get the files correctly identified in your repo by implementing an override in the .gitattributes file or add a modeline comment to the .json files.

The repo you referenced does the former as you can see here.