Document all situtions of git pull

We should document all different git pull situations so that our code is able to handle them.

1. Normal Git Pull - local is behind remote - no conflicts
2. Git pull - local is behind remote and has commits - no conflicts

1. 1. How to assert that the commit and pull is fast-forward?
2. Git pull - local is behind remote and has commits - with conflicts
   1. This is a non-fast-forward commit with merge conflicts

This task is only for documentation that helps us in improving our own implementations to handle such situations.