title: Send document to telegram bot using python-telegram-bot Package
body: <p>I am try to build a telegram bot using python with python-telegram-bot Package and its working with text commands now i try to send a document to user</p>
  <p>my code like</p>
  <pre><code>def start(update, context):
  
  return update.message.download(open('cv.pdf', 'rb'))
  </code></pre>
  <p>but it show a error like <code>return update.message.download(open('cv.pdf', 'rb')) AttributeError: 'Message' object has no attribute 'download'</code></p>
  <p>Then how to send a document file to user any way ?</p>