title: Git Branches - How to have a clean release branch without submodules
body: <p>I have a git repo for my project which is loosely based on GitFlow. I have a master branch, development branch (where all the work gets done) and a release branch.</p>
  
  <p>My repo depends on a few submodules, which I want to continue to track as these submodules get updated, however, I don't want my release branch to contain the submodules in their entirety (tests, docs, et al) I just want my release branch to contain the "product" of the submodule.</p>
  
  <p>My development branch contains everything, as does master. Development periodically gets merged into master. My release branch is currently master, but I just want a clean release branch that isn't stuff full of my development files.</p>
  
  <p>I have attached a rough sketch in case it helps. <img src="https://i.stack.imgur.com/DM84O.png" alt="My Git Repo Sketch"></p>
  
  <p>How do I do this?</p>