title: prefixing github page with www return 404
body: <p>I have a Github page set up and I noticed when I try to open it with 'www' added, I am getting 404ed, I don't understand what may be the cause for it.</p>
  
  <p>Its the case for any github page, I am using a public page as an example here:</p>
  
  <p><a href="https://square.github.io/" rel="nofollow noreferrer">https://square.github.io/</a> works flawlessly whereas <a href="https://www.square.github.io/" rel="nofollow noreferrer">https://www.square.github.io/</a> seems to return a security warning followed by a 404</p>
  
  <p>I am curious to understand what might be causing this problem.</p>
  
  <p>PS- I don't have very good understanding of Publishing websites or HTML, I am expecting it may as well be a very silly doubt from my end</p>