VS Code contributes example

package.json

"contributes": {
        "commands": [
            {
                "command": "extension.createGist",
                "title": "Create Gist"
            }
        ],
        "menus": {
            "editor/context": [
                {
                    "command": "extension.createGist",
                    "group": "YourGroup@1"
                }
            ]
        }
    },