firebase.json

{
  "database": {
    "rules": "database.rules.json"
  },
  "hosting": {
    "public": "dist",
    "target": "stable",
    "cleanUrls": true,
    "redirects": [
      //////////////////////////////////////////////////////////////////////////////////////////////
      // README:
      //   Redirects must also be handled by the ServiceWorker. If you add a redirect rule here,
      //   make sure it is compatible with the configuration in `ngsw-config.json`.
      //////////////////////////////////////////////////////////////////////////////////////////////

      // Strip off the `.html` extension, because Firebase will not do this automatically any more
      // (unless the new URL points to an existing file, which is not necessarily the case here).
      { "type": 301, "source": "/:somePath*/:file.html", "destination": "/:somePath*/:file" },
      { "type": 301, "source": "/:topLevelFile.html", "destination": "/:topLevelFile" },
      { "type": 301, "source": "/guide/v6/migration", "destination": "https://v6.rxjs.dev/guide/v6/migration" },
      { "type": 301, "source": "/guide/v6/pipeable-operators", "destination": "https://v6.rxjs.dev/guide/v6/pipeable-operators" }
    ],
    "rewrites": [
      {
        "source": "**/!(*.*)",
        "destination": "/index.html"
      }
    ],
    "headers": [
      {
        "source": "/",
        "headers": [
          {
            "key": "Link",
            "value": "</generated/navigation.json>;rel=preload;as=fetch,</generated/docs/index.json>;rel=preload;as=fetch"
          }
        ]
      }
    ]
  }
}