title: GIT: Commit only some changes to current branch and the rest to a new branch
body: <p>Like an idiot, I made changes out of scope of my current branch.</p>
  
  <p>I changed 5 files</p>
  
  <pre><code> M  app/form_models/car_registration/basics.rb
  M   app/form_models/car_registration/horse.rb
  M   app/views/car_registration/basics.rb
  M   app/views/car_registration/horse.html.erb
  M   spec/factories/car.rb
  M   spec/form_models/car_registration/basic_spec.rb
  </code></pre>
  
  <p>I would like to commit my basics.rb files to my branch, basics, and my horse.rb files to a new branch, horse.  I already did  git checkout -b horse, and all the files displayed. I have not committed yet. What do I do?</p>