message: docs: restore link to lightweight token page in left nav
  After recent correction to left nav TOC, the link to this new page was temporarily removed. This restores it to next, because the page is not yet available in stable.
  PR Close
diff: "url": "guide/creating-libraries",
  "title": "Creating Libraries",
  "tooltip": "Extend Angular by creating, publishing, and using your own libraries."
  + },
  + {
  + "url": "guide/lightweight-injection-tokens",
  + "title": "Lightweight Injection Tokens for Libraries",
  + "tooltip": "Optimize client app size by designing library services with lightweight injection tokens."
  }
  ]
  },
  