message: fix(docs-infra): add v7 in versions dropdown
  Fixes
  PR Close
diff: }
  ],
  "docVersions": [
  + {
  + "title": "v7",
  + "url": "https://v7.angular.io/"
  + },
  {
  "title": "v6",
  - "url": "https://v6.angular.io"
  + "url": "https://v6.angular.io/"
  },
  {
  "title": "v5",
  - "url": "https://v5.angular.io"
  + "url": "https://v5.angular.io/"
  },
  {
  "title": "v4",
  - "url": "https://v4.angular.io"
  + "url": "https://v4.angular.io/"
  },
  {
  "title": "v2",
  - "url": "https://v2.angular.io"
  + "url": "https://v2.angular.io/"
  }
  ]
  }
  