Examine source code of Last Modified

{
  "manifest_version": 3,
  "name": "Last Modified",
  "version": "1.0",
  "browser_specific_settings": {
    "gecko": {
      "id": "last-modified@github.ende25",
      "strict_min_version": "109.0"
    }
  },
  "description": "Muestra la última fecha de modificación de la página actual",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "activeTab",
    "scripting"
  ],
  "action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  }
}