Examine source code of Medium Shortcuts

{
  "name": "Medium Shortcuts",
  "description": "This adds a list of keyboard shortcuts to the Medium editor window.",
  "version": "1.0.6",
  "manifest_version": 2,
  "content_scripts": [
    {
      "matches": [
        "https://medium.com/*"
      ],
      "js": [
        "index.js"
      ],
      "css": [
        "index.css"
      ]
    }
  ],
  "icons": {
    "16": "keyboard_16.png",
    "48": "keyboard_48.png",
    "128": "keyboard_128.png"
  }
}