Manifest.json : What is wrong with this file?

{
  "name": "Play Next : YouTube",
  "version": "0.1.1",
  "manifest_version": 3,
  "description": "Add videos to queue",
  "homepage_url": "https://www.youtube.com",
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "browser_action": {
    "default_popup": "popup.html"
  },
  "permissions": [
    "cookies",
    "tabs",
    "storage",
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": ["*://*.youtube.com/*"],
      "css": ["src/inject/inject.css"],
      "js": ["src/inject/inject.js"]
    }
 ],
  "web_accessible_resources": [
    {
      "resources": ["src/inject/main.js"]
    }
  ]
}

Error : Invalid value for ‘web_accessible_resources[0]’. Entry must at least have resources, and one other valid key.

Question : Can someone provide a nice tutorial for Manifest V3, with examples?