firebase.json

{
  "hosting": {
    "public": "out",
    "ignore": [
      "firebase.json",
      "**/.*",
      "**/node_modules/**"
    ],
    "//cleanUrls": "Setting this to 'true' allows you to navigate to pages without specifying '.html' (only needed when viewing the app on Firebase hosting)",
    "cleanUrls": true
  },
  "firestore": {
    "rules": "firestore.rules",
    "indexes": "firestore.indexes.json"
  }
}