fix issues brought up in the meeting

Fixed:
  - Specify granularity of feature-branches
  - Stress  that branching models are not enforced by git
  - Explain what is meant by running your own Instance
  - Rebase motivation and example
  - Simplify the Kollison and Cycle part
  - Spelling
  - Mention Editor Integration
  - Motivate diffent execution contexts and how docker helps