title: Update Spring Tool Suite to version 3.9.0 (without reinstall it from zero)
body: <p>I'm using Spring Tool Suite:</p>
  
  <p>Version: 3.8.4.RELEASE</p>
  
  <p>Build Id: 201703310825</p>
  
  <p>Platform: Eclipse Neon.3 (4.6.3)</p>
  
  <p>Today its Dashboard noticed me that the new version 3.9.0 is available.
  I tried to use the options menu "Help -> Check for update" and "Help -> Installation Details -> Update button" but no updates are found.</p>
  
  <p>What is the correct procedure to update it, without to reinstall it from zero?</p>
  
  <p>In this page: "<a href="https://spring.io/tools/sts/all" rel="nofollow noreferrer">https://spring.io/tools/sts/all</a>" there are the "Update Site Archives" and "Update Sites". How I can use them?</p>
  
  <p>Can I extract the archive and overwrite all files?</p>
  
  <p>Or can I use the update site into the menu option "Help -> Install new software" ? (in this case, I have to choose Eclipse 4.6 because it is the current installed version, or can I have to choose Eclipse 4.7 because it is the newer?)</p>
  
  <p>Thanks a lot</p>