Examine source code of RelaxedReader

{
  "manifest_version": 2,
  "name": "RelaxedReader",
  "version": "1.0.2resigned1",
  "icons": {
    "48": "study48.png"
  },
  "browser_action": {
    "default_icon": "study48.png",
    "default_title": "RelaxedReader",
    "default_popup": "app.html"
  },
  "permissions": [
    "activeTab",
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "relaxedreader@citizen428.net",
      "strict_min_version": "53.0"
    }
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Ctrl+Shift+L"
      },
      "description": "Add site to RelaxedReader"
    }
  }
}