Examine source code of Davout

{
  "manifest_version": 3,
  "name": "Davout",
  "description": "A browser extension for displaying League of Legends rank in the Twitch chat.",
  "version": "1.8.0",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "48": "icon/48.png",
    "128": "icon/128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.twitch.tv/*"
      ],
      "js": [
        "contentScript.js"
      ],
      "css": [
        "css/index.css"
      ],
      "run_at": "document_end"
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "img/iron.png",
        "img/bronze.png",
        "img/silver.png",
        "img/gold.png",
        "img/emerald.png",
        "img/platinum.png",
        "img/diamond.png",
        "img/master.png",
        "img/grandmaster.png",
        "img/challenger.png",
        "img/unranked.png",
        "css/index.css"
      ],
      "matches": [
        "*://*.twitch.tv/*"
      ]
    }
  ],
  "host_permissions": [
    "*://*.twitch.tv/*"
  ],
  "externally_connectable": {
    "matches": [
      "https://davout.io/*"
    ]
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "temp@davout",
      "strict_min_version": "109.0"
    }
  }
}