title: How to enable auto-completion with Git [all platforms]
body: <p>How to enable auto-completion with Git?</p>
  
  <p>When using Git on different platforms, auto-completion is not always enabled/available.</p>
  
  <p>Note that this question is NOT a duplicate of <a href="https://apple.stackexchange.com/questions/55875">git auto-complete for <em>branches</em> on the command line</a>, because that question was only about Apple users. This question is mostly the same, but including other platforms too.</p>