title: GitHub include from another repository
body: <p>I'm new to github.</p>
  
  <p>I have a github repo on my machine. I want to include another repo (as a third party) into my repo. I believe I should make a fork first. But how do I include it on my local repo?</p>
  
  <p>I've tried submodules but with no success...</p>
  
  <p>Thanks.</p>