message: build(aio): use http push for navigation.json
diff: "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"
  + }
  + ]
  + }
  ]
  }
  }
  