docs: clarify example in README

[benmccann]

I thought that the config below would be valid since it was demonstrated on the README.

  {
      "typescript": {
        "alwaysTryTypes": true // always try to resolve types under `<root>@types` directory even it doesn't contain any source code, like `@types/unist`
      },

      // use <root>/path/to/folder/tsconfig.json
      "typescript": {
        "project": "path/to/folder"
      },
  }

It turns out the typescript blocks are not merged and overwrite each other. This PR updates the example on the README so as to not demonstrate multiple typescript blocks