Examine source code of felix

{
  "manifest_version": 2,
  "name": "My Addon",
  "version": "1.0",
  "description": "Description here.",
  "icons": {
    "48": "imagini/iconita.jpg"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "index.js"
      ]
    }
  ]
}