Add more motivation for Git to "Preface" chapter

[lnnrtwttkhn]

• [ ] Show the end result: What will I be able to do once I learned Git?
• [ ] Example: How to create a personal website?
• [ ] Demonstrate CI/CD: Website is automatically rebuild
• [ ] Demonstrate public repos related to papers (code sharing)
• [ ] Branches: Usefulness of branches (or tags) for research process: Tag versions of a paper or code related to submission, revision, final publication, etc.
• [ ] Conflict: Demonstrate how conflicts can be reconciled
• [ ] Optional: Show visualization of conflict resoolution (e.g., in RStudio, VSCode or GitKraken)
• [ ] Future career: Emphasize / show NGOs / companies that use Git / have a presence on GitHub
• [ ] Future career: Emphasize the relevance for Data Science Jobs but also other jobs that involve code and data ("Data Literacy"!)
• [ ] Refer to article about AirBnB who uses R and Git: https://www.tandfonline.com/doi/full/10.1080/00031305.2017.1392362
• [ ] Git allows to collaborate with more technical people
• [ ] Collaboration with Git does not mean that you have to wrote code
• [ ] Benefit when using GitHub: Backup
• [ ] You have an issue with your computer. You can just easily move to a different machine, clone a copy and continue working.

Thanks to @anamartinovici for the ideas and suggestions!