Copilot Custom Instructions cannot be defined at the language level

[tspascoal]

I believe that instructions language language specific settings are not supported in instructions as stated in Customizing Copilot

At least if we try to configure it, something like

    "[javascript]": {
        "github.copilot.chat.codeGeneration.instructions": [
    
        ],
    }

We get an warning stating this setting cannot be applied at a language level