Examine source code of a11y-outline

{
  "manifest_version": 3,
  "name": "a11y-outline",
  "author": "Tobias Bengfort",
  "homepage_url": "https://github.com/xi/a11y-outline",
  "description": "navigate page outlines easily",
  "version": "2.3.0",
  "action": {
    "default_title": "A11y Outline",
    "default_icon": "icons/icon-128.png"
  },
  "icons": {
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "background": {
    "scripts": [
      "src/bg.js"
    ]
  },
  "commands": {
    "_execute_action": {
      "suggested_key": {
        "default": "Ctrl+Shift+7"
      }
    },
    "cycle-main": {
      "description": "go to main landmark"
    },
    "next-landmark": {
      "description": "go to next landmark"
    },
    "prev-landmark": {
      "description": "go to previous landmark"
    },
    "next-heading": {
      "description": "go to next heading"
    },
    "prev-heading": {
      "description": "go to previous heading"
    }
  },
  "permissions": [
    "activeTab",
    "scripting"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{34e8d1d4-286c-4cb8-96d3-9eecd0665c0f}"
    }
  }
}