Examine source code of Hacktoberfest Detector

{
  "manifest_version": 2,
  "name": "Hacktoberfest Detector",
  "version": "1.2.4",
  "description": "Detect whether the repository has opted into the 2021 Hacktoberfest.",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "permissions": [],
  "content_scripts": [
    {
      "matches": [
        "*://github.com/*",
        "*://www.github.com/*"
      ],
      "js": [
        "optindetector.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "hacktoberfesttagdetector@marcolussetti.com"
    }
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png"
    }
  }
}