Extend markdown in vscode tmLanguage

Question

I'm trying to add some new coloring to VS code markdown.

Package.json

"contributes": {
    "grammers": [
        {
            "scopeName": "markdown.rise",
            "path": "./syntaxes/markdown.tmLanguage.json",
            "injectTo": [
                "text.html.markdown"
            ]
        }
    ]
}

markdown.tmLanguage.json

{
    "version":"0.0.1",
    "fileTypes":[],
    "injectionSelector": "L:text.html.markdown",
    "name": "markdown",
    "scopeName": "markdown.rise",
    "patterns": [{
        "name": "punctuation.definition.bold.markdown",
        "match": "^\\@\\w+$"
    }]
}

The idea it to color something like @john. But a bit lost on how to make it work.