Update Course for 2025 edition

[enryH]

• move course to GitHub workspaces (away from binder)
• break into sections: introduction, advanced, internals of git

Intro

• use case: Get code of an app from GitHub and run it

Advanced

• use case: Keep track of your own code and make changes

Internal of git

• use case: understand more about the tool itself to be able to reason why something is (not) working