Examine source code of Reading time

{
  "manifest_version": 3,
  "name": "Reading time",
  "version": "1.1.5",
  "browser_specific_settings": {
    "gecko": {
      "id": "ricardo.fernandes@lll"
    }
  },
  "description": "Add the reading time to Chrome Extension documentation articles",
  "content_scripts": [
    {
      "js": [
        "scripts/content.js"
      ],
      "matches": [
        "https://developer.chrome.com/docs/extensions/*",
        "https://developer.chrome.com/docs/webstore/*"
      ]
    }
  ]
}