title: Show diff in file but not allow git to merge them
body: <p>I want to have, <em>by default</em>, some type of files treated as binary but show the diff to the user so they can know what they change.</p>
  
  <p>This is for files that, while a human could understand them, git doesn't really know how to merge them and it can break a project if they are not handled correctly.</p>
  
  <p>Is there any way to obtain this result? I know that I can add in a <code>.gitconfig</code> the option:</p>
  
  <pre><code>[diff "*.unity"]
    textconv = ps2ascii
    binary = true
  </code></pre>
  
  <p>But the problem is that this doesn't work by default, so the user must assign this configuration to their own system.</p>