title: Mongoose pagination case insensitive string sorting
body: <p>I am using NodeJS 12 with Mongoose v5 and the mongoose-paginate-v2 plugin. It is working correctly.</p>
  
  <p><a href="https://www.npmjs.com/package/mongoose-paginate-v2" rel="nofollow noreferrer">https://www.npmjs.com/package/mongoose-paginate-v2</a></p>
  
  <p>Question: Is it possible to set the 'sort' option to be case insensitive with the plugin?</p>
  
  <p>The sort option is returning sorted values in case-sensitive order, so capital 'Z' is ordered before lowercase 'a'.</p>