title: Rubocop only to check modified lines
body: <p>I would like to run rubocop on the terminal only for the lines that I have modified within a git versioned project. Currently, from googling, I see scripts which work on the entire modified file.</p>
  
  <p>I found <a href="https://gist.github.com/skanev/9d4bec97d5a6825eaaf6" rel="noreferrer">this</a> but what I understand from the documentation is that it shows false positives and negatives.</p>