vscode-extension-samples/custom-data-sample/html.html-data.json

{
  "version": 1.1,
  "tags": [{
    "name": "my-button",
    "description": "My button",
    "attributes": [{
      "name": "type",
      "description": "My button type",
      "values": [
        { "name": "alert" }
      ]
    }],
    "references": [
      {
        "name": "Bootstrap buttons",
        "url": "https://getbootstrap.com/docs/4.0/components/buttons/"
      }
    ]
  }]
}